/in/foo.cc: In function 'int main()':
/in/foo.cc:7:9: warning: unused variable 'j' [-Wunused-variable]
   int i,j,k,n,x,y,s=0,x1,y1;
         ^
/in/foo.cc:7:26: warning: variable 'y1' set but not used [-Wunused-but-set-variable]
   int i,j,k,n,x,y,s=0,x1,y1;
                          ^~