diff --git a/src/main/java/lambda/data/Person.java b/src/main/java/lambda/data/Person.java
new file mode 100644
index 0000000..773efac
--- /dev/null
+++ b/src/main/java/lambda/data/Person.java
@@ -0,0 +1,55 @@
+package lambda.data;
+
+import java.util.Objects;
+
+public class Person {
+
+    private final String firstName;
+    private final String lastName;
+    private final int age;
+
+    public Person(String firstName, String lastName, int age) {
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.age = age;
+    }
+
+    public String getFirstName(Person this) {
+        return firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public String getFullName() {
+        return firstName + " " + lastName;
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (this == other) return true;
+        if (other == null || getClass() != other.getClass()) return false;
+        Person person = (Person) other;
+        return age == person.age
+            && Objects.equals(firstName, person.firstName)
+            && Objects.equals(lastName, person.lastName);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(age, firstName, lastName);
+    }
+
+    @Override
+    public String toString() {
+        return "Person@" + hashCode() + ": {"
+             + "firstName='" + firstName + "', "
+             + "lastName='" + lastName + "', "
+             + "age=" + age + "}";
+    }
+}
diff --git a/src/test/java/api/exercise/Exercise1.java b/src/test/java/api/exercise/Exercise1.java
new file mode 100644
index 0000000..29ee8d1
--- /dev/null
+++ b/src/test/java/api/exercise/Exercise1.java
@@ -0,0 +1,113 @@
+package api.exercise;
+
+import lambda.data.Person;
+import org.hamcrest.Matchers;
+import org.junit.jupiter.api.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.BiFunction;
+import java.util.stream.Collectors;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.hasEntry;
+import static org.hamcrest.Matchers.hasKey;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.not;
+
+@SuppressWarnings({"ConstantConditions", "unused", "MismatchedQueryAndUpdateOfCollection"})
+class Exercise1 {
+
+    enum Status {
+        UNKNOWN,
+        PENDING,
+        COMMENTED,
+        ACCEPTED,
+        DECLINED
+    }
+
+    @Test
+    void acceptGreaterThan21OthersDecline() {
+        Person alex = new Person("Алексей", "Мельников", 20);
+        Person ivan = new Person("Иван", "Стрельцов", 24);
+        Person helen = new Person("Елена", "Рощина", 22);
+        Map<Person, Status> candidates = new HashMap<>();
+        candidates.put(alex, Status.PENDING);
+        candidates.put(ivan, Status.PENDING);
+        candidates.put(helen, Status.PENDING);
+
+        BiFunction<? super Person, ? super Status, ? extends Status> greaterThan21 = (p, s) -> p.getAge() > 21 ? Status.ACCEPTED : Status.DECLINED;
+        candidates.replaceAll(greaterThan21);
+
+        assertThat(candidates, Matchers.hasEntry(ivan, Status.ACCEPTED));
+        assertThat(candidates, Matchers.hasEntry(helen, Status.ACCEPTED));
+        assertThat(candidates, Matchers.hasEntry(alex, Status.DECLINED));
+    }
+
+    @Test
+    void acceptGreaterThan21OthersRemove() {
+        Person alex = new Person("Алексей", "Мельников", 20);
+        Person ivan = new Person("Иван", "Стрельцов", 24);
+        Person helen = new Person("Елена", "Рощина", 22);
+        Map<Person, Status> candidates = new HashMap<>();
+        candidates.put(alex, Status.PENDING);
+        candidates.put(ivan, Status.PENDING);
+        candidates.put(helen, Status.PENDING);
+
+        candidates.put(new Person("a", "a", 19), Status.PENDING);
+        candidates.put(new Person("b", "c", 16), Status.PENDING);
+        candidates.put(new Person("b", "c", 5), Status.PENDING);
+
+        candidates = candidates.entrySet().stream()
+                .filter(e -> e.getKey().getAge() > 21)
+                .peek(e -> e.setValue(Status.ACCEPTED))
+                .collect(Collectors.toMap(
+                        Map.Entry::getKey,
+                        Map.Entry::getValue));
+
+        assertThat(candidates, Matchers.hasEntry(ivan, Status.ACCEPTED));
+        assertThat(candidates, Matchers.hasEntry(helen, Status.ACCEPTED));
+        assertThat(candidates, not(hasKey(alex)));
+    }
+
+    @Test
+    void getStatus() {
+        Person alex = new Person("Алексей", "Мельников", 20);
+        Person ivan = new Person("Иван", "Стрельцов", 24);
+        Person helen = new Person("Елена", "Рощина", 22);
+        Map<Person, Status> candidates = new HashMap<>();
+        candidates.put(alex, Status.PENDING);
+        candidates.put(ivan, Status.PENDING);
+
+        Status alexStatus = candidates.getOrDefault(alex, Status.UNKNOWN);
+        Status ivanStatus = candidates.getOrDefault(ivan, Status.UNKNOWN);
+        Status helenStatus = candidates.getOrDefault(helen, Status.UNKNOWN);
+
+        assertThat(alexStatus, is(Status.PENDING));
+        assertThat(ivanStatus, is(Status.PENDING));
+        assertThat(helenStatus, is(Status.UNKNOWN));
+    }
+
+    @Test
+    void putToNewValuesIfNotExists() {
+        Person alex = new Person("Алексей", "Мельников", 20);
+        Person ivan = new Person("Иван", "Стрельцов", 24);
+        Person helen = new Person("Елена", "Рощина", 22);
+        Person dmitry = new Person("Дмитрий", "Егоров", 30);
+        Map<Person, Status> oldValues = new HashMap<>();
+        oldValues.put(alex, Status.PENDING);
+        oldValues.put(dmitry, Status.DECLINED);
+        oldValues.put(ivan, Status.ACCEPTED);
+
+        Map<Person, Status> newValues = new HashMap<>();
+        newValues.put(alex, Status.DECLINED);
+        newValues.put(helen, Status.PENDING);
+
+        // TODO implementation
+        oldValues.forEach(newValues::putIfAbsent);
+
+        assertThat(newValues, hasEntry(alex, Status.DECLINED));
+        assertThat(newValues, hasEntry(ivan, Status.ACCEPTED));
+        assertThat(newValues, hasEntry(helen, Status.PENDING));
+    }
+}