foo.c: In function 'main':
foo.c:14:4: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
  if(max==a)
    ^
foo.c:19:4: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
  if(max==b)
    ^
foo.c:24:4: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
  if(max==c)
    ^
foo.c:7:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d %d", &a ,&b ,&c);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务