#include<bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1010;
vector<int> v[N];
int adjm[N][N], l[N], r[N], bit[N];
bool vis[N][N], in[N];
vector<int> adj[N];
int col[N], ans[N];
bool bipartite(int v, int c = 1) {
if (col[v]) return col[v] == c;
col[v] = c;
for (auto& x : adj[v]) {
if (!bipartite(x, 3 - c)) return false;
}
return true;
}
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
int n, m;
cin >> n >> m;
for (int i = 0;i < m;i++) {
cin >> l[i] >> r[i];
l[i]--, r[i]--;
int nl = l[i], nr = r[i];
for (;nl != nr;nl = (nl + 1) % n) {
if ((int)v[nl].size() <= 2) v[nl].push_back(i);
}
if ((int)v[nr].size() <= 2) v[nr].push_back(i);
}
for (int i = 0;i < n;i++) {
if ((int)v[i].size() <= 1) {
cout << "impossible\n";
return 0;
}
}
for (int i = 0;i < n;i++) {
if ((int)v[i].size() == 2) {
in[v[i][0]] = in[v[i][1]] = 1;
adj[v[i][0]].push_back(v[i][1]);
adj[v[i][1]].push_back(v[i][0]);
}
}
for (int i = 0;i < m;i++) {
if (in[i] && !col[i]) {
if (!bipartite(i)) {
cout << "impossible\n";
return 0;
}
}
}
for (int i = 0;i < m;i++) col[i]--;
for (int i = 0;i < n;i++) {
int bit = 0;
for (auto& x : v[i]) {
if (col[x] != -1) bit |= (1 << col[x]);
}
if (bit == 3) continue;
if (!(bit & 1)) {
for (auto& x : v[i]) {
if (col[x] != -1) continue;
col[x] = 0;
break;
}
}
if (!(bit & 2)) {
for (auto& x : v[i]) {
if (col[x] != -1) continue;
col[x] = 1;
break;
}
}
}
for (int i = 0;i < m;i++) {
if (col[i] == -1) col[i] = 0;
cout << col[i];
}
cout << '\n';
return 0;
}
