View Compilation Error

0_0_31887655_421.cpp:2:1: error: '_int64' does not name a type
 _int64 CN(int n)//Ҫע�⵽��ֵ�ķ�Χ�����Ƕ���64λ��������Ӧ������Ҫע��������ֵ������ʽ 
 ^
0_0_31887655_421.cpp: In function 'int main()':
0_0_31887655_421.cpp:16:2: error: '_int64' was not declared in this scope
  _int64 c;
  ^
0_0_31887655_421.cpp:20:3: error: 'c' was not declared in this scope
   c=1;
   ^
0_0_31887655_421.cpp:26:24: error: 'CN' was not declared in this scope
   printf("%I64d\n",CN(b)*c);
                        ^