Main.c: In function ‘main’:
Main.c:12:2: warning: implicit declaration of function ‘scanf_s’; did you mean ‘scanf’? [-Wimplicit-function-declaration]
   12 |  scanf_s("%d", &n1);
      |  ^~~~~~~
      |  scanf
/usr/bin/ld: /tmp/cck1WMmn.o: in function `main':
Main.c:(.text.startup+0x2d): undefined reference to `scanf_s'
/usr/bin/ld: Main.c:(.text.startup+0x61): undefined reference to `scanf_s'
/usr/bin/ld: Main.c:(.text.startup+0x76): undefined reference to `scanf_s'
/usr/bin/ld: Main.c:(.text.startup+0xe4): undefined reference to `scanf_s'
/usr/bin/ld: Main.c:(.text.startup+0xf5): undefined reference to `scanf_s'
/usr/bin/ld: /tmp/cck1WMmn.o:Main.c:(.text.startup+0x1bf): more undefined references to `scanf_s' follow
collect2: error: ld returned 1 exit status