View Compilation Error

0_0_28226985_17812.cpp:2:1: error: '_int64' does not name a type
 _int64 C_n_m(int n,int m)
 ^
0_0_28226985_17812.cpp: In function 'int main()':
0_0_28226985_17812.cpp:15:5: error: '_int64' was not declared in this scope
     _int64 sum,a[14]={1,0,1,2};
     ^
0_0_28226985_17812.cpp:17:9: error: 'a' was not declared in this scope
         a[i]=(i-1)*(a[i-1]+a[i-2]);
         ^
0_0_28226985_17812.cpp:20:13: error: 'sum' was not declared in this scope
         for(sum=0,i=0;i<=n/2;i++)
             ^
0_0_28226985_17812.cpp:21:27: error: 'C_n_m' was not declared in this scope
             sum+=C_n_m(n,i)*a[i];
                           ^
0_0_28226985_17812.cpp:21:29: error: 'a' was not declared in this scope
             sum+=C_n_m(n,i)*a[i];
                             ^
0_0_28226985_17812.cpp:22:26: error: 'sum' was not declared in this scope
         printf("%I64d\n",sum);
                          ^