/in/foo.c:3:18: warning: built-in function 'round' declared as non-function
 int max=3000,m,n,round=3000;
                  ^~~~~
/in/foo.c: In function 'main':
/in/foo.c:16:6: error: 'i' undeclared (first use in this function)
  for(i=0;i<m;i++)
      ^
/in/foo.c:16:6: note: each undeclared identifier is reported only once for each function it appears in