diff --git a/app/main.py b/app/main.py
index 626f41cf..fbaae223 100644
--- a/app/main.py
+++ b/app/main.py
@@ -1,34 +1,118 @@
+from typing import List
+
+
 class Deck:
-    def __init__(self, row, column, is_alive=True):
-        pass
+    def __init__(self, row: int, column: int, is_alive: bool = True) -> None:
+        self.row = row
+        self.column = column
+        self.is_alive = is_alive
+
+    def fire(self) -> bool:
+        self.is_alive = False
+        return self.is_alive
+
+    def __repr__(self) -> str:
+        return "□" if self.is_alive else "x"
 
 
 class Ship:
-    def __init__(self, start, end, is_drowned=False):
-        # Create decks and save them to a list `self.decks`
-        pass
+    def __init__(self,
+                 start: tuple,
+                 end: tuple,
+                 is_drowned: bool = False
+                 ) -> None:
+        self.is_drowned = is_drowned
+        self.decks = self.create_decks(start, end)
 
-    def get_deck(self, row, column):
-        # Find the corresponding deck in the list
-        pass
+    @staticmethod
+    def create_decks(start: tuple, end: tuple) -> List[Deck]:
+        decks = []
+        if start[0] == end[0]:  # Horizontal
+            first_row = start[0]
+            for col in range(min(start[1], end[1]), max(start[1], end[1]) + 1):
+                decks.append(Deck(first_row, col))
+        elif start[1] == end[1]:  # Vertical
+            first_col = start[1]
+            for row in range(min(start[0], end[0]), max(start[0], end[0]) + 1):
+                decks.append(Deck(row, first_col))
+        return decks
 
-    def fire(self, row, column):
-        # Change the `is_alive` status of the deck
-        # And update the `is_drowned` value if it's needed
-        pass
+    def fire(self, row: int, column: int) -> str:
+        for deck in self.decks:
+            if deck.row == row and deck.column == column:
+                deck.fire()
+                if all(not deck.is_alive for deck in self.decks):
+                    self.is_drowned = True
+                    return "Sunk!"
+                return "Hit!"
+        return "Miss!"
+
+    def __repr__(self) -> str:
+        return "".join(str(deck) for deck in self.decks)
 
 
 class Battleship:
-    def __init__(self, ships):
-        # Create a dict `self.field`.
-        # Its keys are tuples - the coordinates of the non-empty cells,
-        # A value for each cell is a reference to the ship
-        # which is located in it
-        pass
-
-    def fire(self, location: tuple):
-        # This function should check whether the location
-        # is a key in the `self.field`
-        # If it is, then it should check if this cell is the last alive
-        # in the ship or not.
-        pass
+    def __init__(self, ships: list[tuple]) -> None:
+        self.field = [["~" for _ in range(10)] for _ in range(10)]
+        self.ships = [Ship(start, end) for start, end in ships]
+        self.place_ships()
+        self._validate_field()
+
+    def place_ships(self) -> None:
+        for ship in self.ships:
+            for deck in ship.decks:
+                row, col = deck.row, deck.column
+                self.field[row][col] = "□"
+
+    def fire(self, location: tuple) -> str:
+        row, col = location
+        for ship in self.ships:
+            result = ship.fire(row, col)
+
+            if result == "Hit!":
+                self.field[row][col] = "*"
+                return result
+
+            if result == "Sunk!":
+                for deck in ship.decks:
+                    self.field[deck.row][deck.column] = "x"
+                return result
+
+        return "Miss!"
+
+    def print_field(self) -> None:
+        for row in self.field:
+            print(" ".join(row))
+
+    def _validate_field(self) -> None:
+        ship_lengths = [len(ship.decks) for ship in self.ships]
+        if len(self.ships) != 10:
+            raise ValueError("There should be exactly 10 ships.")
+        if ship_lengths.count(1) != 4:
+            raise ValueError("There should be exactly 4 single-deck ships.")
+        if ship_lengths.count(2) != 3:
+            raise ValueError("There should be exactly 3 double-deck ships.")
+        if ship_lengths.count(3) != 2:
+            raise ValueError("There should be exactly 2 three-deck ships.")
+        if ship_lengths.count(4) != 1:
+            raise ValueError("There should be exactly 1 four-deck ship.")
+        if not self._check_no_neighbors():
+            raise ValueError("Ships should not be located "
+                             "in neighboring cells.")
+
+    def _check_no_neighbors(self) -> bool:
+        directions = [(-1, -1), (-1, 0), (-1, 1), (0, -1),
+                      (0, 1), (1, -1), (1, 0), (1, 1)
+                      ]
+        for ship in self.ships:
+            for deck in ship.decks:
+                row, col = deck.row, deck.column
+                for dr, dc in directions:
+                    nr, nc = row + dr, col + dc
+                    if (0 <= nr < 10
+                            and 0 <= nc < 10
+                            and self.field[nr][nc] == "□"
+                            and (nr, nc)
+                            not in [(d.row, d.column) for d in ship.decks]):
+                        return False
+        return True