/in/foo.c: In function 'main':
/in/foo.c:5:2: warning: implicit declaration of function 'scanf_s' [-Wimplicit-function-declaration]
  scanf_s("%d %d %d %d", &n, &m, &l, &r);
  ^~~~~~~
/in/foo.c:27:2: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
  printf("%d\n", sum);
  ^~~~~~
/in/foo.c:27:2: warning: incompatible implicit declaration of built-in function 'printf'
/in/foo.c:27:2: note: include '<stdio.h>' or provide a declaration of 'printf'
/tmp/ccK39syj.o: In function `main':
foo.c:(.text.startup+0x41): undefined reference to `scanf_s'
foo.c:(.text.startup+0x7a): undefined reference to `scanf_s'
foo.c:(.text.startup+0xd2): undefined reference to `scanf_s'
collect2: error: ld returned 1 exit status