import core.bitop;
import std.algorithm;
import std.ascii;
import std.bigint;
import std.conv;
import std.functional;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.random;
import std.typecons;
import std.container;

alias sread = () => readln.chomp();
alias route = Tuple!(long, "From", long, "To");
long bignum = 1_000_000_007;
auto dp = new long[](100_100);

T lread(T = long)()
{
    return readln.chomp.to!T();
}

T[] aryread(T = long)()
{
    return readln.split.to!(T[])();
}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}

void main()
{
    long n, m;
    scan(n, m);
    auto fromto = new long[](0);
    foreach (_; 0 .. m)
    {
        long f, t;
        scan(f, t);
        if (f == 1)
            fromto ~= t;
        if (t == n)
            fromto ~= f;
    }
    if (fromto.canGo)
        writeln("POSSIBLE");
    else
        writeln("IMPOSSIBLE");
}

auto canGo(T)(T a)
{
    a.sort();
    foreach (i, _; a)
    {
        if(i > 0)
            if(a[i - 1] == a[i])
                return true;
    }
    return false;
}