View Compilation Error

0_0_32877191_26064.cpp: In function 'matrix mul(matrix, matrix)':
0_0_32877191_26064.cpp:16:40: error: 'struct matrix' has no member named 'a'
                 temp.mat[i][j] = (temp.a[i][j] + a.mat[i][k] * b.mat[k][j]) % mod;
                                        ^