#include<bits/stdc++.h>

#define REP(i, a, b) for(register int i = (a); i < (b); i++)

#define _for(i, a, b) for(register int i = (a); i <= (b); i++)

using namespace std;

const int MAXN = 1e3 + ;

struct Edge{ int to, next; };

Edge e[MAXN << ];

int head[MAXN], ans[MAXN], tot;

int vis[MAXN], n, m, t;

void AddEdge(int from, int to)

{

    e[tot] = Edge{to, head[from]};

    head[from] = tot++;

}

bool dfs(int u)

{

    vis[u] = -;

    for(int i = head[u]; ~i; i = e[i].next)

    {

        int v = e[i].to;

        if(vis[v] == -) return false;

        if(!vis[v] && !dfs(v)) return false;

    }

    vis[u] = ; ans[--t] = u;

    return true;

}

bool toopsort()

{

    memset(vis, , sizeof(vis));

    t = n + ;

    _for(i, , n)

        if(!vis[i] && !dfs(i))

            return false;

    return true;

}

int main()

{

    while(~scanf("%d%d", &n, &m) && n)

    {

        memset(head, -, sizeof(head)); tot = ;

        _for(i, , m)

        {

            int u, v;

            scanf("%d%d", &u, &v);

            AddEdge(u, v);

        }

        if(toopsort())

        {

            _for(i, , n - ) printf("%d ", ans[i]);

            printf("%d\n", ans[n]);

        }

        else puts("NO");

    } 

    return ;

}

#include<bits/stdc++.h>

#define REP(i, a, b) for(register int i = (a); i < (b); i++)

#define _for(i, a, b) for(register int i = (a); i <= (b); i++)

using namespace std;

const int MAXN = 1e3 + ;

struct Edge{ int to, next; };

Edge e[MAXN << ];

int head[MAXN], ans[MAXN], tot;

int d[MAXN], n, m, t, cnt;

void AddEdge(int from, int to)

{

    e[tot] = Edge{to, head[from]};

    head[from] = tot++;

}

bool toopsort()

{

    queue<int> q;

    _for(i, , n)

         if(!d[i])

            q.push(i);

    while(!q.empty())

    {

        int u = q.front(); q.pop();

        ans[++cnt] = u;

        for(int i = head[u]; ~i; i = e[i].next)

        {

            int v = e[i].to;

            d[v]--; if(!d[v]) q.push(v);

        }

    }

    return cnt == n;

}

int main()

{

    while(~scanf("%d%d", &n, &m) && n)

    {

        memset(head, -, sizeof(head)); tot = ;

        memset(d, , sizeof(d));

        _for(i, , m)

        {

            int u, v;

            scanf("%d%d", &u, &v);

            AddEdge(u, v);

            d[v]++;

        }

        cnt = ;

        if(toopsort())

        {

            _for(i, , n - ) printf("%d ", ans[i]);

            printf("%d\n", ans[n]);

        }

        else puts("NO");

    } 

    return ;

}