View Compilation Error

0_0_26689256_25612.cpp: In function 'int main()':
0_0_26689256_25612.cpp:75:41: error: no match for 'operator%' (operand types are 'Matrix' and 'long long int')
             ans=Mat_mul(m_fpow(a,n-2),b)%(mod-1);
                                         ^