/**

* ZOJ 1015 Fishing Net

*

* 2005/05/04 By adai

*/

#include <iostream>

#include <iomanip>

#include <cstdio>

#include <cmath>

#include <cstring>

#include <string>

#include <algorithm>

#include <vector>

#include <list>

#include <deque>

#include <set>

using namespace std;

#ifdef WIN32

#define for if(0); else for

#endif

//quick sort

int cmp(const void *t1, const void *t2) {

int *a, *b;

a = (int*)t1;

b = (int*)t2;

return (*b) - (*a);

}

#define MAXN 1001

int n, line;

int adj[MAXN][MAXN], adjNum[MAXN];

int label[MAXN], num[MAXN], numI[MAXN];

int m[MAXN];

int maximum_cardinality_search() {

memset(label, 0, sizeof(label));

for (int i = n; i >= 1; --i) {

int v = n + 1, tmp = -1;

for (int j = n; j >= 1; --j) {

if (num[j] == 0 && label[j] > tmp) {

tmp = label[j], v = j;

}

}

num[v] = i;

numI[i] = v;

for (int j = 0; j < adjNum[v]; ++j) {

int w = adj[v][j];

if (num[w] == 0) ++label[w];

}

}

return 0;

}

int perfect_elimination_order() {

for (int i = 1; i <= n - 1; ++i) {

int v = numI[i], w, first = 1;

for (int j = 0; j < adjNum[v]; ++j) {

w = adj[v][j];

if (num[w] > num[v]) {

if (first) {

first = 0;

m[v] = w;

}

else {

if (num[w] < num[m[v]]) m[v] = w;

}

}

}

for (int j = 0; j < adjNum[v]; ++j) {

w = adj[v][j];

if (num[m[v]] < num[w]) {

int flag = 0;

for (int k = 0; k < adjNum[m[v]]; ++k) {

if (w == adj[m[v]][k]) {

flag = 1;

break;

}

}

if (flag == 0) return 0;

}

}

}

return 1;

}

int Run() {

memset(adjNum, 0, sizeof(adjNum));

memset(num, 0, sizeof(num));

while (line--) {

int a, b;

scanf("%d %d", &a, &b);

adj[a][adjNum[a]++] = b;

adj[b][adjNum[b]++] = a;

}

for (int i = 1; i <= n; ++i) qsort(adj[i], adjNum[i], sizeof(int), cmp);

maximum_cardinality_search();

if (perfect_elimination_order()) printf("Perfect\n\n");

else printf("Imperfect\n\n");

return 0;

}

int main() {

while (scanf("%d %d", &n, &line) && n + line) {

Run();

}

return 0;

}