diff --git a/app/main.py b/app/main.py
index 626f41cf..92830f95 100644
--- a/app/main.py
+++ b/app/main.py
@@ -1,34 +1,116 @@
 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,
+            end: tuple,
+            is_drowned: bool = False
+    ) -> None:
+        self.decks = []
+        self.is_drowned = is_drowned
+        for i in range(
+                max(
+                    (end[0] - start[0]),
+                    (end[1] - start[1])
+                ) + 1
+        ):
+            if start[0] != end[0]:
+                self.decks.append(Deck(start[0] + i, start[1]))
+            elif start[1] != end[1]:
+                self.decks.append(Deck(start[0], start[1] + i))
+            else:
+                self.decks.append(Deck(start[0], start[1]))
 
-    def get_deck(self, row, column):
-        # Find the corresponding deck in the list
-        pass
+    def get_deck(
+            self,
+            row: int,
+            column: int
+    ) -> Deck:
+        for deck in self.decks:
+            if deck.row == row and deck.column == column:
+                return deck
 
-    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
+    ) -> None:
+        deck = self.get_deck(row, column)
+        if deck.is_alive:
+            deck.is_alive = False
+        if all(deck.is_alive is False for deck in self.decks):
+            self.is_drowned = True
 
 
 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,
+    ) -> None:
+        self.field = {}
+        for ship in ships:
+            current_ship = Ship(ship[0], ship[1])
+            for deck in current_ship.decks:
+                self.field[deck.row, deck.column] = current_ship
+        self._validate_field()
+
+    def fire(
+            self,
+            location: tuple
+    ) -> str:
+        if location in self.field:
+            self.field[location].fire(location[0], location[1])
+            if self.field[location].is_drowned:
+                return "Sunk!"
+            return "Hit!"
+        return "Miss!"
+
+    def print_field(self) -> None:
+        field = [["~"] * 10 for _ in range(10)]
+        for (row, column), ship in self.field.items():
+            deck = ship.get_deck(row, column)
+            if ship.is_drowned:
+                field[row][column] = "x"
+            elif not deck.is_alive:
+                field[row][column] = "*"
+            else:
+                field[row][column] = u"\u25A1"
+        for row in field:
+            print(" ".join(row))
+
+    def _validate_field(self) -> None:
+        if len(set(self.field.values())) != 10:
+            raise Exception("Invalid number of ships")
+        ships_lengths = []
+        for ship in set(self.field.values()):
+            ships_lengths.append(len(ship.decks))
+        if ships_lengths.count(1) != 4:
+            raise Exception("Invalid number of ships")
+        if ships_lengths.count(2) != 3:
+            raise Exception("Invalid number of ships")
+        if ships_lengths.count(3) != 2:
+            raise Exception("Invalid number of ships")
+        if ships_lengths.count(4) != 1:
+            raise Exception("Invalid number of ships")
+        for (row, column), ship in self.field.items():
+            for deck_row in range(-1, 2):
+                for deck_column in range(-1, 2):
+                    if deck_row == 0 and deck_column == 0:
+                        pass
+                    elif (row + deck_row, column + deck_column) in self.field:
+                        near_ship = self.field[
+                            row + deck_row, column + deck_column
+                        ]
+                        if near_ship != ship:
+                            raise Exception("Invalid location of ships")