/in/foo.c: In function 'main':
/in/foo.c:4:13: error: expected ')' before '<' token
  int i,j,n(n<20);
             ^
/in/foo.c:5:14: error: 'n' undeclared (first use in this function)
  scanf("%d",&n);
              ^
/in/foo.c:5:14: note: each undeclared identifier is reported only once for each function it appears in