#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<vector>
#include<queue>
#include<algorithm>
#include<set>
#define clr(x,y) memset(x,y,sizeof(x))
using namespace std;
const int maxn=1010;vector<int> construct(int n,vector<int> adj[maxn])
{static int rank[maxn],label[maxn];clr(rank,-1);clr(label,0);priority_queue<pair<int,int> > heap;for(int i=1;i<=n;i++)heap.push(make_pair(0,i));for(int i=n-1;i>=0;i--){while(true){int u=heap.top().second;heap.pop();if(rank[u]==-1){rank[u]=i;for(vector<int>:: iterator iter=adj[u].begin();iter!=adj[u].end();++iter){if(rank[*iter]==-1){label[*iter]++;heap.push(make_pair(label[*iter],*iter));}}break;}}}vector<int> result(n);for(int i=1;i<=n;i++)    {result[rank[i]]=i;}   return result;
}bool check(int n,vector<int>adj[maxn],vector<int> ord)
{static bool mark[maxn];static int rank[maxn];for(int i=0;i<n;i++)rank[ord[i]]=i;clr(mark,0);for(int i=0;i<n;i++){vector<pair<int,int> >tmp;for(vector<int>::iterator iter=adj[ord[i]].begin();iter!=adj[ord[i]].end();++iter)if(!mark[*iter])tmp.push_back(make_pair(rank[*iter],*iter));sort(tmp.begin(),tmp.end());if(tmp.size()){int u=tmp[0].second;set<int> tmpAdj;for(vector<int>::iterator iter=adj[u].begin();iter!=adj[u].end();++iter){tmpAdj.insert(*iter);}for(int i=1;i<(int)tmp.size();++i){if(!tmpAdj.count(tmp[i].second))return false;}}mark[ord[i]]=true;
}
return true;
}bool is_chordal(int nodeCount,vector<pair<int,int> >edges)
{int n=nodeCount;vector<int>adj[maxn];for(int i=0;i<=n;i++)adj[i].clear();for(vector<pair<int,int> >::iterator iter=edges.begin();iter!=edges.end();++iter){adj[iter->first].push_back(iter->second);adj[iter->second].push_back(iter->first);}   return check(n,adj,construct(n,adj));
}int main()
{int n,m;while(scanf("%d%d",&n,&m)){if(n==0&&m==0)return 0;vector<pair<int,int> >ed;for(int i=0;i<m;i++){int a,b;scanf("%d%d",&a,&b);ed.push_back(make_pair(a,b));}if(is_chordal(n,ed))printf("Perfect\n\n");else printf("Imperfect\n\n");}return 0;
}