View Compilation Error

0_0_13915887_15370.cpp: In function 'int main()':
0_0_13915887_15370.cpp:4:2: error: '_int64' was not declared in this scope
  _int64 a[51]={0,1};
  ^
0_0_13915887_15370.cpp:7:3: error: 'a' was not declared in this scope
   a[n]=a[n-1]+a[n-2];
   ^
0_0_13915887_15370.cpp:9:20: error: 'a' was not declared in this scope
   printf("%I64d\n",a[n]);
                    ^