/in/foo.c:4:1: warning: return type defaults to 'int' [-Wimplicit-int]
 main() {
 ^~~~
/in/foo.c: In function 'main':
/in/foo.c:7:2: warning: implicit declaration of function 'scanf_s' [-Wimplicit-function-declaration]
  scanf_s("%d %d", &n, &x);
  ^~~~~~~
/in/foo.c:20:2: warning: implicit declaration of function 'getch' [-Wimplicit-function-declaration]
  getch();
  ^~~~~
/tmp/ccAxApm2.o: In function `main':
foo.c:(.text.startup+0x18): undefined reference to `scanf_s'
foo.c:(.text.startup+0x87): undefined reference to `getch'
collect2: error: ld returned 1 exit status