#include <iostream>
#include <cstring>

using namespace std;

const int N = 2e4 + 10;

int h[N], e[N], ne[N], idx;
int d[N];
int n, m;
int q[N], hh = 0, tt = -1;
int w[N], res;

void add(int a, int b){
    e[idx] = b, ne[idx] = h[a], h[a] = idx ++;
}

bool topsort(){
    for(int i = 1; i <= n; i ++) 
        if(!d[i]) q[++ tt] = i, w[i] = 100;

    while(hh <= tt){
        int t = q[hh ++];
        for(int i = h[t]; i != -1; i = ne[i]){
            int j = e[i];
            d[j] --;
            w[j] = w[t] + 1;
            if(!d[j]) q[++ tt] = j;
        }
    }
    return tt == n - 1;
}

int main(){
    memset(h, -1, sizeof h);
    cin >> n >> m;
    for(int i = 0; i < m; i ++){
        int a, b;
        cin >> a >> b;
        add(b, a);
        d[a] ++;
    }
    if(topsort()){
        for(int i = 1; i <= n; i ++) res += w[i];
        cout << res;
    }
    else cout << "Poor Xed";
    return 0;
}