#include "transfer.h"
#include <bits/stdc++.h>
using namespace std;
vector<int> get_attachment(vector<int> source) {
int K = 9;
if (source.size() == 63) {
K = 7;
}
int n = source.size();
vector<int> ret(K);
for (int i = 0; i < n; i++) {
for (int j = 0; j < K - 1; j++) {
if ((i + 1) >> j & 1) {
ret[j] ^= source[i];
}
}
ret[K - 1] ^= source[i];
}
return ret;
}
vector<int> retrieve(vector<int> data) {
int K = 9;
if (data.size() < 255) {
K = 7;
}
int n = data.size();
int f = 0;
for (int i = 0; i < n - K; i++) {
f ^= data[i];
}
vector<int> ans(n - K);
for (int i = 0; i < n - K; i++) {
ans[i] = data[i];
}
if (f == data.back()) {
return ans;
}
vector<int> r(8);
for (int i = 0; i < n - K; i++) {
for (int j = 0; j < K - 1; j++) {
if ((i + 1) >> j & 1) {
r[j] ^= data[i];
}
}
}
int pos = 0;
for (int i = 0; i < K - 1; i++) {
if (r[i] != data[n - K + i]) {
pos += (1 << i);
}
}
if (pos != 0) {
pos--;
ans[pos] ^= 1;
}
return ans;
}
/*
5
0 011001010110110110100111110011010111111111111000101011100101001
7 011001010110110110100111110011010111111111111000101011100101001
62 011001010110110110100111110011010111111111111000101011100101001
63 011001010110110110100111110011010111111111111000101011100101001
-1 011001010110110110100111110011010111111111111000101011100101001
*/
