#include<cmath>
#include<bits/stdc++.h>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<string>
using namespace std;
#define LL int
int read()
{
int x=0,w=1;
char ch=0;
while(ch<'0'||ch>'9')
{
if(ch=='-')
w=-1;
ch=getchar();
}
while(ch>='0'&&ch<='9')
{
x=x*10+ch-'0';
ch=getchar();
}
return w*x;
}
void print(int x)//输出优化
{
if(x<0)//如果x为负数,先输出负号,再把它变成正数处理
{
putchar('-');
x=-x;
}
if(x>9)
{
print(x/10);
}
putchar(x%10+'0');
}