/in/foo.c: In function 'main':
/in/foo.c:45:9: warning: implicit declaration of function 'scanf_s' [-Wimplicit-function-declaration]
  while (scanf_s("%d", &arr[i]) != EOF && getchar() != '\n') 
         ^~~~~~~
/tmp/ccgRulUN.o: In function `main':
foo.c:(.text.startup+0x56): undefined reference to `scanf_s'
collect2: error: ld returned 1 exit status