View Compilation Error

0_0_30360648_20425.cpp: In function 'int solve(ll)':
0_0_30360648_20425.cpp:79:9: error: 'res' was not declared in this scope
         res=Add(res,Mul(n/l/l,Sub(S(r),S(l-1))));
         ^
0_0_30360648_20425.cpp:81:12: error: 'res' was not declared in this scope
     return res;
            ^