foo.c: In function 'main':
foo.c:6:9: warning: implicit declaration of function 'scanf_s'; did you mean 'scanf'? [-Wimplicit-function-declaration]
    6 |         scanf_s("%d %d", &x1,&x2);
      |         ^~~~~~~
      |         scanf
foo.c:10:16: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   10 |         while (a = x1 % x2)
      |                ^
/nix/store/vhf2cr6immz4qdxd83y025fnxim8mmfg-binutils-2.38/bin/ld: /tmp/ccJtoeKY.o: in function `main':
foo.c:(.text.startup+0x26): undefined reference to `scanf_s'
collect2: error: ld returned 1 exit status

[Hydro](https://hydro.ac)提供评测服务