Mate In 3, Not 4
White to play and mate in 3. (Black plays optimally throughout.)
Give the coordinates of the landing squares of White's first, second, and third moves as a six-digit number. E.g. if White's first move was Kc1, the first two digits would be 31; if White's second move was Nd3, the third and fourth digits would be 43, and so on.