View Compilation Error

0_0_18920502_3478.cpp: In function 'int main()':
0_0_18920502_3478.cpp:45:36: error: 'mod' was not declared in this scope
   printf("%lld\n",C(n-m*k-1,m-1)*n%mod*qpow(m,p-2)%p);
                                    ^