/in/foo.cc: In function 'int main()':
/in/foo.cc:34:8: warning: unused variable 'j' [-Wunused-variable]
  int i,j,k,l,m,n;
        ^
/in/foo.cc:34:10: warning: unused variable 'k' [-Wunused-variable]
  int i,j,k,l,m,n;
          ^
/in/foo.cc:34:12: warning: unused variable 'l' [-Wunused-variable]
  int i,j,k,l,m,n;
            ^
/in/foo.cc:34:14: warning: unused variable 'm' [-Wunused-variable]
  int i,j,k,l,m,n;
              ^
/in/foo.cc:34:16: warning: unused variable 'n' [-Wunused-variable]
  int i,j,k,l,m,n;
                ^
/in/foo.cc: In function 'int cal(int, int)':
/in/foo.cc:31:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^