foo.c: In function 'main':
foo.c:20:2: warning: implicit declaration of function 'scanf_s'; did you mean 'scanf'? [-Wimplicit-function-declaration]
   20 |  scanf_s("%d%d", &n1, &n2);
      |  ^~~~~~~
      |  scanf
/usr/bin/ld: /tmp/ccgrsRXM.o: in function `main':
foo.c:(.text.startup+0x4f): undefined reference to `scanf_s'
/usr/bin/ld: foo.c:(.text.startup+0x7c): undefined reference to `scanf_s'
/usr/bin/ld: foo.c:(.text.startup+0xbc): undefined reference to `scanf_s'
collect2: error: ld returned 1 exit status

[Hydro](https://hydro.ac)提供评测服务