лошарский бп

#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <iomanip>
using namespace std;
const int N = 2e5 + 7, INF = 1e8;
long double v1, v2, t, d, l,r, mid;

bool check(long double v) {
    return (v1 * t) / (v - v1) - (v2 * t) / (v - v2) <= d;
}

int main()
{
    cin >> v1 >> v2 >> t >> d;
    if (v1 < v2) {
        swap(v1, v2);
    }
    l = v1;
    r = 200;
    for (int i = 0; i < 100; i++) {
        mid = (l + r) / 2;
        if (check(mid)) {
             r = mid;
        }
        else {
            l = mid;
        }
    }
    cout << fixed << setprecision(10) << l;
}