View Compilation Error

0_0_30509375_20488.cpp: In function 'long long int quickpow(long long int, long long int, long long int)':
0_0_30509375_20488.cpp:30:21: error: 'a' was not declared in this scope
             ans=ans*a;
                     ^
0_0_30509375_20488.cpp:35:9: error: expected ';' before 'if'
         if(n>mod)n=n%mod+mod;
         ^