#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
int cnt[N], l[N], r[N], n, m;
vector<pair<int, int>> adj[N * 2];
vector<int> path;
bool vis[N * 2];
bool dfs(int u) {
if (u == n) return 1;
if (vis[u]) return 0;
vis[u] = 1;
for (auto e : adj[u]) {
int v, i; tie(v, i) = e;
path.push_back(i);
if (dfs(v)) return 1;
path.pop_back();
}
return 0;
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> m;
for (int i = 1; i <= m; i++)
cin >> l[i] >> r[i];
{
int x = *min_element(l + 1, l + m + 1);
for (int i = 1; i <= m; i++) {
l[i] -= x; r[i] -= x;
if (r[i] < 0) r[i] += n;
}
}
for (int i = 1; i <= m; i++)
if (l[i] <= r[i]) {
cnt[l[i]]++; cnt[r[i] + 1]--;
adj[l[i]].emplace_back(r[i] + 1, i);
adj[l[i] + n].emplace_back(r[i] + 1 + n, i);
} else {
cnt[0]++; cnt[l[i]]++; cnt[r[i] + 1]--;
adj[l[i]].emplace_back(r[i] + 1 + n, i);
}
for (int i = 0; i < n; i++) {
cnt[i + 1] += cnt[i];
if (cnt[i] < 2)
return cout << "impossible", 0;
if (cnt[i] > 2) {
adj[i + 1].emplace_back(i, 0);
adj[i + 1 + n].emplace_back(i + n, 0);
}
}
if (dfs(0)) {
memset(cnt, 0, sizeof cnt);
for (int i : path) cnt[i] = 1;
for (int i = 1; i <= m; i++)
cout << cnt[i];
} else cout << "impossible";
}
