foo.c: In function 'gys':
foo.c:14:1: warning: control reaches end of non-void function [-Wreturn-type]
14 | }int main()
| ^
foo.c: In function 'main':
foo.c:17:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
17 | scanf("%d%d", &a, &b);
| ^~~~~~~~~~~~~~~~~~~~~
foo.c:19:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
19 | scanf("%d%d", &c, &d);
| ^~~~~~~~~~~~~~~~~~~~~
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