var su = 4;
var grid = new Array(2, 9, 1,  5, 7, 3,  4, 6, 8, 
                     7, 5, 8,  6, 4, 9,  2, 3, 1, 
                     6, 4, 3,  2, 1, 8,  5, 9, 7, 

                     9, 7, 6,  3, 2, 5,  8, 1, 4, 
                     1, 3, 5,  4, 8, 7,  6, 2, 9, 
                     8, 2, 4,  9, 6, 1,  7, 5, 3, 

                     4, 8, 2,  1, 9, 6,  3, 7, 5, 
                     5, 6, 9,  7, 3, 4,  1, 8, 2, 
                     3, 1, 7,  8, 5, 2,  9, 4, 6);
var guess = new Array(81);
var clues = new Array(0, 4, 8, 11, 12, 14, 16, 19, 23, 24, 28, 29, 30, 32, 36, 40, 44, 48, 49, 50, 51, 52, 56, 57, 61, 66, 68, 69, 72, 73, 79, 80);