#include "transfer.h"
#include <bits/stdc++.h>
using namespace std;
vector<int> get_attachment(vector<int> source) {
int N = source.size();
vector<int> ret(__lg(N-1) + 2, 0);
for (int i = 0; i <= __lg(N-1); ++i) {
for (int j = 1; j <= N; ++j) {
ret[i] ^= (j >> i & 1) * source[j-1];
}
ret.back() ^= ret[i];
}
return ret;
}
vector<int> retrieve(vector<int> data) {
int N = (data.size() < 255 ? 63 : 255);
int K = data.size() - N;
vector<int> ret(begin(data) + N, end(data));
for (int i = 0; i < K-1; ++i) ret.back() ^= ret[i];
if (ret.back() == 1) return vector<int>(begin(data), begin(data) + N);
int sus = 0;
for (int i = 0; i < K-1; ++i) {
for (int j = 1; j <= N; ++j) {
ret[i] ^= (j >> i & 1) * data[j-1];
}
if (ret[i]) sus |= (1 << i);
}
if (sus > 0) data[sus-1] ^= 1;
return vector<int>(begin(data), begin(data) + N);
}
