View Compilation Error

0_0_17677422_26091.cpp: In function 'long long int get_k(int, int)':
0_0_17677422_26091.cpp:56:69: error: 'mod' was not declared in this scope
             ans = ( ans + 1LL * phi[n / i] * get_k ( i, m / i ) ) % mod ;
                                                                     ^