#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>
#include <map>
#include <stack>
#include <queue>
#include <cstdlib>
#include <numeric>


/*
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::::. <!!!!!! !!!!!!!!!! ,$ .nn.' "$$ P"   <!!!!!!!!!!!' .::::::::::::::::
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MMMP <!!! dMMMb "?$$P" uMMM>;!!! 4MMMMMMMr`:::::::::.........:::::::::::::
MMP';!!! ;MMMMMMn,.".uMMMMM ;!!! MMMMMMMMM,`::::::::::::::::::::::::::::::
MM ;!!!! MMMMMMMMMMMMMMMMMM !!!! MMMMMMMMMb `:::::::::::::::::::::::::::::
M" !!!! uMMMMMMMMMMMMMMMMMP !!! ;MMMMMMMMMMx :::::::::::::::::::::::::::::
P.!!!! ,MMMMMMMMMMMMMMMMMM ,!!! MMMMMMMMMMMMx`::::::::::::::::::::::::::::
!!!!> MMMMMMMMMMMMMMMMMMP !!!',MMMMMMMMMMMMM `:::::::::::::::::::::::::::
*/


int main()
{
	long long n, m;

	std::cin >> n >> m;

	std::vector<long long> v(n);

	for (long long i = 0; i < m; i++) {
		long long a, b;

		std::cin >> a >> b;

		if (a == 1 || a == n) {
			v[b - 1]++;
		}
		if (b == 1 || b == n) {
			v[a - 1]++;
		}
	}

	for (size_t i = 0; i < v.size(); i++) {
		if (v[i] == 2) {
			std::cout << "POSSIBLE" << std::endl;
			return 0;
		}
	}

	std::cout << "IMPOSSIBLE" << std::endl;

	return 0;
}

Measured memory_bytes: 1792