View Compilation Error

0_0_26158086_9160.cpp: In function 'int main()':
0_0_26158086_9160.cpp:131:24: error: no match for 'operator*' (operand types are 'Mat' and 'long long int')
         long long ans=a*(b^(n-1)).m[0][0];
                        ^
0_0_26158086_9160.cpp:131:24: note: candidate is:
0_0_26158086_9160.cpp:11:5: note: Mat operator*(Mat, Mat)
 Mat operator * (Mat a,Mat b){
     ^
0_0_26158086_9160.cpp:11:5: note:   no known conversion for argument 2 from 'long long int' to 'Mat'