/in/foo.c: In function 'main':
/in/foo.c:6:17: warning: unused variable 'b' [-Wunused-variable]
  double x3,y3,a,b,si,co;
                 ^
/in/foo.c:5:20: warning: unused variable 'm' [-Wunused-variable]
  int x1,y1,x2,y2,n,m;
                    ^
/in/foo.c:5:18: warning: unused variable 'n' [-Wunused-variable]
  int x1,y1,x2,y2,n,m;
                  ^