Tablita

#include <iostream>
#include <cmath>
#include <fstream>
using namespace std;
ifstream fin("tablita.in");
ofstream fout("tablita.out");
int main()
{
    int n, delta, g;
    double x;
    fin>>n;
    delta=1+8*n;
    x=(-1+sqrt(delta))/2.0;
    if (x==int(x)) g=x;
    else g=x+1;
    fout<<g;
    fin.close();
    fout.close();
    return 0;
}