int read()//快读
{
	int x=0,f=1;
	int ch=getchar();
	while(ch<'0'||ch>'9') if(ch=='-') f=-1,ch=getchar();
	while(ch>='0'&&ch<='9') x=x*10+ch-48,ch=getchar();
	return x*f;
}


int read()//快读
{
	int x=0,f=1;
	int ch=getchar();
	while(ch<'0'||ch>'9') {if(ch=='-') f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9') x=x*10+ch-48,ch=getchar();
	return x*f;
}