/in/foo.cc: In function 'int main()':
/in/foo.cc:5:18: warning: unused variable 'j' [-Wunused-variable]
  long long a,b,i,j,k,ans=0;
                  ^
/in/foo.cc:5:20: warning: unused variable 'k' [-Wunused-variable]
  long long a,b,i,j,k,ans=0;
                    ^