+---+---+---+---+---+6 | | | 0 | | | +---+---+---+---+---+5 | 0 | | | | | +---+---+---+---+---+4 | | 1 | ? | | 0 | +---+---+---+---+---+3 | | 1 | ? | 1 | | +---+---+---+---+---+2 | 0 | | | | | +---+---+---+---+---+1 | | 0 | | | | +---+---+---+---+---+See? The frog can be anywhere on the ?-squares.