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缺省源
#include<bits/stdc++.h>
#define int long long
#define N 1000100
using namespace std;
inline int read(){int x=0,f=1;char ch=getchar();while(!isdigit(ch)){f=ch!='-';ch=getchar();}while(isdigit(ch)){x=(x<<1)+(x<<3)+(ch^48);ch=getchar();}return f?x:-x;}
signed main()