View Compilation Error

0_0_30259779_20288.cpp: In function 'long long int inv(long long int)':
0_0_30259779_20288.cpp:15:9: error: 'a' was not declared in this scope
         a*=a;
         ^
0_0_30259779_20288.cpp:16:12: error: expected primary-expression before '%' token
         a%=%mod;
            ^
0_0_30259779_20288.cpp: In function 'int main()':
0_0_30259779_20288.cpp:27:26: error: 'm' was not declared in this scope
         scanf("%d%d",&n,&m);
                          ^
0_0_30259779_20288.cpp:34:63: error: 'x' was not declared in this scope
             sum[i]=(sum[i-1]+(a+(1-p+mod)%mod*(a+sum[i-1]-sum[x-1]+mod)%mod*inv(p)%mod))%mod;
                                                               ^
0_0_30259779_20288.cpp:36:15: error: conflicting declaration 'int r'
         int l,r;
               ^
0_0_30259779_20288.cpp:28:19: note: previous declaration as 'long long int r'
         long long r,s,a,p;
                   ^