#include <iostream>
#include <fstream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>
#include <bitset>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <ctime>
#define LL long long
#define Vi vector<int>
#define Si set<int>
#define readf freopen("input.txt","r",stdin)
#define writef freopen("output.txt","w",stdout)
#define FU(i,a)......
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