Эволюция

#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <queue>
using namespace std;

int main() {

    std::ifstream fin("input.txt");
    std::ofstream fout("output.txt");

    int k;
    long long v1, v2;
    fin >> k >> v1 >> v2;
    vector<vector<long long>> dad(2);

    while (v1 > 1 || v2 > 1) {

        v1 /= 2;
        if (v1 != 0)
            dad[0].push_back(v1);

        v2 /= 2;
        if (v2 != 0)
            dad[1].push_back(v2);

    }

    long long max = 0;
    for (int i = dad[0].size() - 1; i >= 0; --i) {
        for (int j = dad[1].size() - 1; j >= 0; --j) {
            if (dad[0][i] == dad[1][j]) {
                max = dad[0][i];
            }
        }
    }

    fout << max;

    return 0;

}