#include <iostream>
#include <iomanip>
#include <algorithm>
#include <bitset>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <cmath>
#include <time.h>
#include <random>
#include <string>
#include <cassert>
#include <vector>
#include <ostream>
#include <istream>
#include <stack>
#include <deque>
#include <queue>
#include <functional>

using namespace std;

#define int long long
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define pii pair<int, int>
#define ld long double

ostream& operator << (ostream &a, const vector<int> &b) {
    for (auto k : b) cout << k << " ";
    return a;
}

#ifdef LOCAL
    #define dbg(x) cout << #x << " : " << (x) << "\n";
    const int INF = 1e18;
//    const int mod = 2600000069;
//    const int p = 10;
//    const ld PI = 3.1415926535;
#else
    #define dbg(x)
    const int INF = 1e18;
//    const int mod = 2600000069;
//    const int p = 179;
//    const ld PI = 3.1415926535;
#endif

//#pragma GCC optimize("Ofast,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,sse3,sse4")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("fast-math")
//#pragma GCC target("avx2")
//#pragma GCC optimize("section-anchors")
//#pragma GCC optimize("profile-values,profile-reorder-functions,tracer")
//#pragma GCC optimize("vpt")
//#pragma GCC optimize("rename-registers")
//#pragma GCC optimize("move-loop-invariants")
//#pragma GCC optimize("unswitch-loops")
//#pragma GCC optimize("function-sections")
//#pragma GCC optimize("data-sections")

int n, m;
const int MAXN = 110;
vector<vector<int>> g;
vector<pii> comp;
vector<pii> used;

int cnt1, cnt2, t = 0;
bool ok = 1;

int rev(int k) {
    if (k == 1) return 2;
    if (k == 2) return 1;
}

void dfs(int v, int c) {
    used[v].first = c;
    used[v].second = t;
    if (c == 1) cnt1++;
    else cnt2++;
    for (auto u : g[v]) {
        if (!used[u].first) {
            dfs(u, rev(c));
        } else if (used[u].first == c) {
            ok = 0;
        }
    }
}

bool dp[MAXN][MAXN], par[MAXN][MAXN];

signed main() {
//    ios_base::sync_with_stdio(0);
//    cin.tie(0);
//    cout.tie(0);
    cin >> n >> m;
    n += n;
    g.resize(n);
    used.assign(n, {0, -1});
    int u, v;
    for (int i = 0; i < m; i++) {
        cin >> u >> v;
        u--, v--;
        g[u].pb(v);
        g[v].pb(u);
    }
    for (int i = 0; i < n; i++) {
        if (!used[i].first) {
            cnt1 = cnt2 = 0;
            dfs(i, 1);
            comp.pb({cnt1, cnt2});
            t++;
        }
    }
    if (!ok) {
        cout << "IMPOSSIBLE\n";
        return 0;
    }
    int sz = t;
    dp[0][comp[0].first] = dp[0][comp[0].second] = 1;
    for (int i = 1; i < sz; i++) {
        for (int j = 0; j <= n / 2 - comp[i].first; j++) {
            if (dp[i - 1][j]) {
                dp[i][j + comp[i].first] = 1;
                par[i][j + comp[i].first] = 0;
            }
        }
        for (int j = 0; j <= n / 2 - comp[i].second; j++) {
            if (dp[i - 1][j]) {
                dp[i][j + comp[i].second] = 1;
                par[i][j + comp[i].second] = 1;
            }
        }
    }
    if (!dp[sz - 1][n / 2]) {
        cout << "IMPOSSIBLE\n";
        return 0;
    }
    int cur = n / 2;
    vector<int> ans1, ans2;
    for (int i = sz - 1; i >= 0; i--) {
        if (!par[i][cur]) {
            for (int j = 0; j < n; j++) {
                if (used[j].second == i) {
                    if (used[j].first == 1) ans1.pb(j + 1);
                    else ans2.pb(j + 1);
                }
            }
            cur -= comp[i].first;
        } else {
            for (int j = 0; j < n; j++) {
                if (used[j].second == i) {
                    if (used[j].first == 1) ans2.pb(j + 1);
                    else ans1.pb(j + 1);
                }
            }
            cur -= comp[i].second;
        }
    }
    assert(ans1.size() == n / 2 && ans2.size() == n / 2);
    cout << ans1 << "\n" << ans2;
}
/*

*/