IsFibo challenge in C++

gistfile1.cpp

/*Author: Gelidus(gelidus@hotmail.sk)*/
 
#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
 
 
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int testCases; cin >> testCases;
   
    double root5 = sqrt(5);
    double phi = (1 + root5) / 2;
   
    for(int i = 0; i < testCases; i++) {
        long long number; cin >> number;
       
        long long id = (long long)floor(log(number * root5) / log(phi) + 0.5);
        long long  u = (long long)floor(pow(phi, id) / root5 + 0.5);
       
        cout << (u == number ? "IsFibo" : "IsNotFibo") << endl;
    }
   
    return 0;
}