diff --git a/app/main.py b/app/main.py
index 626f41cf..835e8999 100644
--- a/app/main.py
+++ b/app/main.py
@@ -1,34 +1,106 @@
+from typing import List, Tuple, Optional
+
+
 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
 
 
 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[int, int],
+                 end: Tuple[int, int], is_drowned: bool = False) -> None:
+        self.start = start
+        self.end = end
+        self.is_drowned = is_drowned
+        self.decks = self._create_decks()
 
-    def get_deck(self, row, column):
-        # Find the corresponding deck in the list
-        pass
+    def _create_decks(self) -> List[Deck]:
+        decks = []
+        if self.start[0] == self.end[0]:  # Horizontal ship
+            for col in range(self.start[1], self.end[1] + 1):
+                decks.append(Deck(self.start[0], col))
+        else:  # Vertical ship
+            for row in range(self.start[0], self.end[0] + 1):
+                decks.append(Deck(row, self.start[1]))
+        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 get_deck(self, row: int, column: int) -> Optional[Deck]:
+        for deck in self.decks:
+            if deck.row == row and deck.column == column:
+                return deck
+        return None
+
+    def fire(self, row: int, column: int) -> bool:
+        deck = self.get_deck(row, column)
+        if deck:
+            deck.is_alive = False
+            if all(not d.is_alive for d in self.decks):
+                self.is_drowned = True
+            return True
+        return False
 
 
 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[Tuple[int, int],
+                                         Tuple[int, int]]]) -> None:
+        self.field = {}
+        self.ships = []
+        for ship_coords in ships:
+            ship = Ship(*ship_coords)
+            self.ships.append(ship)
+            for deck in ship.decks:
+                self.field[(deck.row, deck.column)] = ship
+        self._validate_field()
+
+    def fire(self, location: Tuple[int, int]) -> str:
+        if location in self.field:
+            ship = self.field[location]
+            hit = ship.fire(*location)
+            if hit:
+                if ship.is_drowned:
+                    return "Sunk!"
+                return "Hit!"
+        return "Miss!"
+
+    def print_field(self) -> None:
+        field = [["~" for _ in range(10)] for _ in range(10)]
+        for ship in self.ships:
+            for deck in ship.decks:
+                if deck.is_alive:
+                    field[deck.row][deck.column] = "□"
+                else:
+                    if ship.is_drowned:
+                        field[deck.row][deck.column] = "x"
+                    else:
+                        field[deck.row][deck.column] = "*"
+        for row in 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 4 single-deck ships.")
+        if ship_lengths.count(2) != 3:
+            raise ValueError("There should be 3 double-deck ships.")
+        if ship_lengths.count(3) != 2:
+            raise ValueError("There should be 2 three-deck ships.")
+        if ship_lengths.count(4) != 1:
+            raise ValueError("There should be 1 four-deck ship.")
+        if not self._check_no_adjacent_ships():
+            raise ValueError("Ships should not be "
+                             "located in neighboring cells.")
+
+    def _check_no_adjacent_ships(self) -> bool:
+        directions = [(-1, -1), (-1, 0), (-1, 1),
+                      (0, -1), (0, 1), (1, -1), (1, 0), (1, 1)]
+        for (row, col) in self.field:
+            for dx, dy in directions:
+                nx, ny = row + dx, col + dy
+                if 0 <= nx < 10 and 0 <= ny < 10 and (nx, ny) in self.field:
+                    if self.field[(nx, ny)] != self.field[(row, col)]:
+                        return False
+        return True