记录编号	98733	评测结果	AAAAAAAAAA
题目名称	[HAOI 2006]受欢迎的牛	最终得分	100
用户昵称	LuciFer_T-J	是否通过	通过
代码语言	C++	运行时间	0.041 s
提交时间	2014-04-24 15:31:56	内存使用	1.13 MiB

#include<cstring>
#include<iostream>
#include<cstdio>

using namespace std;
#define __________________ 10005
#define ___________________ 50005
struct node{
	int __________, ___________;
}________________[___________________];
int _________________[__________________],____[___________________];
int _[__________________],______[__________________],_____[__________________],___[__________________],__[__________________];
bool ____________________[__________________];
int ______________;
char _______________;
int n,m,s,_______,___s,________,_________;

void _____________(int __________,int ___________){
	________________[++s].__________=__________;
	________________[s].___________=___________;
	____[s]=_________________[__________];
	_________________[__________]=s;
}


void ____________(int x){
	int i;
	
	_______++;
	_[x]=______[x]=_______;
	_____[++________]=x;
	____________________[x]=1;
	for (i=_________________[x];i;i=____[i]){
		if (!_[________________[i].___________]){
			____________(________________[i].___________);
			______[x]=min(______[x],______[________________[i].___________]);
		}
		else{
			if (____________________[x]){
				______[x]=min(______[x],_[________________[i].___________]);
			}
		}
	}
	if (______[x]==_[x]){
		___s++;
		while (_____[________+1]!=x){
			___[_____[________]]=___s;
			__[___s]++;
			____________________[_____[________]]=0;
			________--;
		}
	}
}


void _____________________(){
	int i;
	memset(____________________,1,sizeof(____________________));
	for (i=1;i<=m;i++){
		if (___[________________[i].__________]==___[________________[i].___________]) continue;
		____________________[___[________________[i].__________]]=0;
	}
}

int ______________________(){
	while (!isdigit(_______________=getchar()));
	______________=_______________-'0';
	while (isdigit(_______________=getchar())){
		______________=______________*10+_______________-'0';
	}
	return ______________;
}

int main(){
	freopen("cow.in","r",stdin);
	freopen("cow.out","w",stdout);
	int i,__________,___________;
	n=______________________();
	m=______________________();
	s=0;
	for (i=1;i<=m;i++){
		__________=______________________();
		___________=______________________();
		_____________(__________,___________);
	}
	_______=0;
	________=0;
	___s=0;
	for (i=1;i<=n;i++){
		if (_[i]) continue;
		____________(i);
	}
	_____________________();
	_________=0;
	for (i=1;i<=___s;i++){
		if (____________________[i]){
			if (_________) {
				cout<<0<<endl;
				return 0;
			}
			_________=__[i];
		}
	}
	cout<<_________<<endl;
	return 0;
}