View Compilation Error

0_0_29967835_3799.cpp: In function '__int128 ksm(ll, ll)':
0_0_29967835_3799.cpp:11:28: error: 'mod' was not declared in this scope
         if (b&1) res=res*a%mod;
                            ^
0_0_29967835_3799.cpp:12:15: error: 'mod' was not declared in this scope
         a=a*a%mod;
               ^
0_0_29967835_3799.cpp:16:1: error: expected ';' before '}' token
 }
 ^
0_0_29967835_3799.cpp: In function 'int main()':
0_0_29967835_3799.cpp:40:38: error: 'pow_mod' was not declared in this scope
             res = res*pow_mod(x,p-2,p)%p;
                                      ^