prog.c: In function ‘main’:
prog.c:6:2: warning: implicit declaration of function ‘scanf_s’; did you mean ‘scanf’? [-Wimplicit-function-declaration]
scanf_s("%d", &a);
^~~~~~~
scanf
/usr/bin/ld: /home/2VIzDz/ccvb8lUi.o: in function `main':
prog.c:(.text.startup+0x2f): undefined reference to `scanf_s'
collect2: error: ld returned 1 exit status