foo.c: In function 'main':
foo.c:23:16: warning: format '%lld' expects argument of type 'long long int', but argument 2 has type 'int' [-Wformat=]
   23 |     printf("%lld ", gcd(a, b));
      |             ~~~^    ~~~~~~~~~
      |                |    |
      |                |    int
      |                long long int
      |             %d
foo.c: In function 'gcd':
foo.c:17:1: warning: control reaches end of non-void function [-Wreturn-type]
   17 | }
      | ^

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