View Compilation Error

0_0_22642239_8411.cpp: In function 'long long int qpow(long long int, long long int)':
0_0_22642239_8411.cpp:57:27: error: 'mod' was not declared in this scope
         if(n&1) ret=ret*x%mod;
                           ^
0_0_22642239_8411.cpp:58:15: error: 'mod' was not declared in this scope
         x=x*x%mod; 
               ^