#include "souvenirs.h"
#include <utility>
#include <vector>
void buy_souvenirs(int N, long long P0) {
// std::pair<std::vector<int>, long long> res = transaction(3);
std::pair<std::vector<int>, long long> res;
if (N == 2) {
res = transaction(P0 - 1);
return;
}
if (N == 3) {
// P0 > x > y
long long x, y;
res = transaction(P0 - 1);
if ((int) res.first.size() == 1) {
x = P0 - 1 - res.second;
res = transaction(x);
} else {
long long sum = P0 - 1 - res.second;
// x + y = sum
// y * 2 < sum
long long mnX = sum / 2 + 1;
res = transaction(mnX - 1);
}
return;
}
std::vector<long long> p(N, 0);
std::vector<int> cnt(N, 0);
p[0] = P0;
for (int i = 1; i < N; i++) {
res = transaction(p[i - 1] - 1);
cnt[i]++;
p[i] = p[i - 1] - 1;
if ((int) res.first.size() > 1 || res.second > 0) p[i]--;
if ((int) res.first.size() > 1) cnt[res.first[1]]++;
while (cnt[i] < i) {
res = transaction(p[i]);
++cnt[i];
}
}
return;
}
