快读

int read()
{
	int w=1, s=0;
	char ch=getchar();
	while(ch<'0' || ch>'9') { if(ch=='-') w=-1; ch=getchar(); }
	while(ch>='0'&& ch<='9'){ s=s*10+ch-'0';    ch=getchar(); }
	return s*w; 
}