#include<iostream>
#include<cstdio>
#include<vector>
using namespace std;
int main()
{
    _int64 x;
    vector <double> y;
    while(cin >> x)
    {
        y.push_back(sqrt(1.0*x));
    }
    for(int i=y.size()-1;i>=0;i--)
        printf("%0.4f\n",y[i]);
    return 1;
}

I'm having CE,but in my computer it compiled normally?

#include <cmath>

try to use:
typedef long long _int64;