Джип

#define _USE_MATH_DEFINES
#include <iostream>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <vector>
#include <stdio.h>
#include <cmath>
#include <math.h>
#include <queue>
#include <stack>
#include <climits>
#include <deque>
#include <ctime>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int ui;

#define mh() make_heap()
#define poph() pop_heap()
#define pushh() push_heap()
#define sor(n) n.begin(), n.end()
#define mp make_pair

ll Round(double k)
{
    if (k - int(k) < 1e-9)
        return int(k);
    else
        return int(k)+1;
}
int main()
{
    ll sp, S;
    cin >> S >> sp;
    double sum = 0;
    double i = 0;
    double sc=0;
    do
    {
        i++;
        double d = sp / (i*2.0 - 1);
        if (sum + d >= S)break;
        sum += d;
        sc+=sp;
    }
    while (true);
    double prom = S - sum;
    double answ = sc + prom*(i*2.0 - 1);
    cout << Round(answ);
    system("pause");
    return 0;
}