View Compilation Error

0_0_37255230_21044.cpp: In function 'int main()':
0_0_37255230_21044.cpp:8:54: error: 'scanf_s' was not declared in this scope
  while (scanf_s(" % c % c % c\n", &a[0], &a[1], &a[2]) != EOF) {
                                                      ^