View Compilation Error

0_0_16897428_16851.cpp: In function 'matrix mul(matrix, matrix)':
0_0_16897428_16851.cpp:27:63: error: 'mod' was not declared in this scope
     C.mat[i][j] = (C.mat[i][j] + A.mat[i][k] * B.mat[k][j]) % mod;
                                                               ^
0_0_16897428_16851.cpp: In function 'int main()':
0_0_16897428_16851.cpp:58:48: error: invalid types 'int[int]' for array subscript
   for(int i = 1; i <= n + 2; i++) B.mat[i[n + 2] = 1;
                                                ^
0_0_16897428_16851.cpp:58:53: error: expected ']' before ';' token
   for(int i = 1; i <= n + 2; i++) B.mat[i[n + 2] = 1;
                                                     ^