foo.c: In function 'main':
foo.c:22:11: warning: format '%d' expects argument of type 'int', but argument 2 has type 'long long int' [-Wformat=]
   22 |  printf("%d",a*b/gcd(a,b));
      |          ~^  ~~~~~~~~~~~~
      |           |     |
      |           int   long long int
      |          %lld
foo.c:21:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   21 |  scanf("%lld%lld",&a,&b);
      |  ^~~~~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务