View Compilation Error

0_0_18502156_4278.cpp: In function 'Matrix MulModSprase(Matrix, Matrix)':
0_0_18502156_4278.cpp:236:90: error: 'MOD' was not declared in this scope
                     res.mat[i][k] = (res.mat[i][k] + left.mat[i][j] * right.mat[j][k]) % MOD;
                                                                                          ^