#include <bits/stdc++.h> using namespace std; pair<vector<int>, long long> transaction(long long M); void buy_souvenirs(int N, long long P0) { vector<long long> bestM(N, -1); for (long long M = 1; M < P0; M++) { auto res = transaction(M); for (int t : res.first) { if (bestM[t] == -1) bestM[t] = M; } } for (int i = 1; i < N; i++) { for (int cnt = 0; cnt < i; cnt++) { transaction(bestM[i]); } } }