/in/foo.c: In function 'main':
/in/foo.c:7:2: error: unknown type name '__int64'
  __int64 n;
  ^~~~~~~
/in/foo.c:9:10: warning: implicit declaration of function 'scanf_s' [-Wimplicit-function-declaration]
  while (~scanf_s("%I64d", &n))
          ^~~~~~~