View Compilation Error

0_0_29204275_24687.cpp:2:11: error: '::main' must return 'int'
 void main()
           ^
0_0_29204275_24687.cpp: In function 'int main()':
0_0_29204275_24687.cpp:5:37: error: 'scanf_s' was not declared in this scope
  while (scanf_s("&I64X&I64X", &a, &b) != EOF)
                                     ^