CodeForces 412D Giving Awards

                                                                                                                   D. Giving Awards

                                                                                            time limit per test      1 second

                                                                                         memory limit per test     256 megabytes

input

standard input

output

standard output

The employees of the R1 company often spend time together: they watch football, they go camping, they solve contests. So, it's no big deal that sometimes someone pays for someone else.

Today is the day of giving out money rewards. The R1 company CEO will invite employees into his office one by one, rewarding each one for the hard work this month. The CEO knows who owes money to whom. And he also understands that if he invites personx to his office for a reward, and then immediately invite persony, who has lent some money to person x, then they can meet. Of course, in such a situation, the joy of personx from his brand new money reward will be much less. Therefore, the R1 CEO decided to invite the staff in such an order that the described situation will not happen for any pair of employees invited one after another.

However, there are a lot of employees in the company, and the CEO doesn't have a lot of time. Therefore, the task has been assigned to you. Given the debt relationships between all the employees, determine in which order they should be invited to the office of the R1 company CEO, or determine that the described order does not exist.

Input

The first line contains space-separated integers n andm — the number of employees in R1 and the number of debt relations. Each of the following m lines contains two space-separated integersa_i,b_i(1 ≤ a_i, b_i ≤ n; a_i ≠ b_i), these integers indicate that the person number a_i owes money to a person a numberb_i. Assume that all the employees are numbered from 1 ton.

It is guaranteed that each pair of people p,q is mentioned in the input data at most once. In particular, the input data will not contain pairsp, q andq, p simultaneously.

Output

Print -1 if the described order does not exist. Otherwise, print the permutation ofn distinct integers. The first number should denote the number of the person who goes to the CEO office first, the second number denote the person who goes second and so on.

If there are multiple correct orders, you are allowed to print any of them.

Sample test(s)

Input

2 11 2

Output

2 1 

Input

3 31 22 33 1

Output

2 1 3 

链接：http://codeforces.com/problemset/problem/412/D      

题目大意：

R1公司的CEO要给员工发奖金，员工一个个地进CEO的办公室领奖金。但有的员工之间有债务关系，若A君欠B君的钱，当A君领完奖金后下一个领奖金的是B君的时候，他们就会相遇，A君就要马上还钱给B君，那么A君领到奖金的高兴心情也就变得没有那么高兴了。CEO不希望出现这种情况，要你帮他列出一个不会发生这种情况的召唤员工的顺序~若无这种顺序则输出-1.（不会出现A欠B钱，B也欠A钱的情况）

代码：

#include <iostream>#include <vector>#include <string.h>using namespace std;vector<int> g[30005];int vis[30005];void dfs(int u){    if(vis[u]) return;    vis[u]=1;    for(int i=0;i<g[u].size();i++)    dfs(g[u][i]);    cout<<u<<" "<<endl;}int main(){    int n,m;    while(cin>>n>>m)    {        memset(vis,0,sizeof(vis));        while(m--)        {            int a,b;            cin>>a>>b;            g[a].push_back(b);        }        for(int i=1;i<=n;i++)        {            if(!vis[i])            dfs(i);        }        cout<<endl;    }    return 0;}