Problem #PRU-115384

Problem

A game of ’Battleships’ has a fleet consisting of one $1\times 4$ square, two $1\times 3$ squares, three $1\times 2$ squares, and four $1\times 1$ squares. It is easy to distribute the fleet of ships on a $10\times 10$ board, see the example below. What is the smallest square board on which this fleet can be placed? Note that by the rules of the game, no two ships can be placed on horizontally, vertically, or diagonally adjacent squares.