/in/foo.cc: In function 'int main()':
/in/foo.cc:13:10: warning: unused variable 's' [-Wunused-variable]
  int n,k,s=0,s1=0,s2=0;
          ^
/in/foo.cc:13:14: warning: unused variable 's1' [-Wunused-variable]
  int n,k,s=0,s1=0,s2=0;
              ^~
/in/foo.cc:13:19: warning: unused variable 's2' [-Wunused-variable]
  int n,k,s=0,s1=0,s2=0;
                   ^~