View Compilation Error

0_0_16502948_29796.cpp: In function 'int main()':
0_0_16502948_29796.cpp:4:2: error: '_int64' was not declared in this scope
  _int64 sum,i,n;
  ^
0_0_16502948_29796.cpp:5:23: error: 'n' was not declared in this scope
  while(scanf("%I64d",&n)!=EOF)
                       ^
0_0_16502948_29796.cpp:7:3: error: 'sum' was not declared in this scope
   sum=1;
   ^
0_0_16502948_29796.cpp:8:7: error: 'i' was not declared in this scope
   for(i=1;i<=n;i++)
       ^