View Compilation Error

0_0_32278429_26052.cpp: In function 'long long int inv(long long int)':
0_0_32278429_26052.cpp:3:20: error: 'M' was not declared in this scope
     return pow( n, M - 2 )%M;
                    ^
0_0_32278429_26052.cpp:3:26: error: 'pow' was not declared in this scope
     return pow( n, M - 2 )%M;
                          ^