foo.c: In function 'main':
foo.c:7:2: warning: implicit declaration of function 'scanf_s'; did you mean 'scanf'? [-Wimplicit-function-declaration]
  scanf_s("%d%d", &n1, &n2);
  ^~~~~~~
  scanf
/tmp/cc226e4I.o: In function `main':
foo.c:(.text.startup+0x30): undefined reference to `scanf_s'
foo.c:(.text.startup+0x59): undefined reference to `scanf_s'
foo.c:(.text.startup+0x91): undefined reference to `scanf_s'
collect2: error: ld returned 1 exit status

[Hydro](https://hydro.ac)提供评测服务