/in/foo.c: In function 'main':
/in/foo.c:76:5: warning: implicit declaration of function 'scanf_s' [-Wimplicit-function-declaration]
     scanf_s("%d %d", &k, &n);
     ^~~~~~~
/tmp/ccjNXD7V.o: In function `main':
foo.c:(.text.startup+0x1e): undefined reference to `scanf_s'
collect2: error: ld returned 1 exit status