View Compilation Error

0_0_19586143_13743.cpp: In function 'long long int fastMultiplication(long int, long int, long int)':
0_0_19586143_13743.cpp:8:25: error: 'p' was not declared in this scope
             ans=(ans+a)%p;
                         ^
0_0_19586143_13743.cpp:9:17: error: 'p' was not declared in this scope
         a=(a*2)%p;
                 ^