/in/foo.cc: In function 'int main()':
/in/foo.cc:28:25: warning: unused variable 'n1' [-Wunused-variable]
     int x1, y1, x2, y2, n1, n2;
                         ^~
/in/foo.cc:28:29: warning: unused variable 'n2' [-Wunused-variable]
     int x1, y1, x2, y2, n1, n2;
                             ^~