/in/foo.c: In function 'main':
/in/foo.c:9:6: error: 'm' undeclared (first use in this function)
   if(m==2){
      ^
/in/foo.c:9:6: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:5:8: warning: variable 'y' set but not used [-Wunused-but-set-variable]
  int x,y,z,l,r=0;
        ^