#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
int cnt[N], l[N], r[N], n, m;
vector<pair<int, int>> g[N * 2];
vector<int> path;
int vis[N * 2], tim;
bool dfs(int u, int p) {
if(u == p) return 1;
if(vis[u] == tim) return 0;
vis[u] = tim;
for(auto e : g[u]) {
int v, i;
tie(v, i) = e;
path.push_back(i);
if (dfs(v, p)) 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]--;
g[l[i]].emplace_back(r[i] + 1, i);
g[l[i] + n].emplace_back(r[i] + 1 + n, i);
} else {
cnt[0]++;
cnt[l[i]]++;
cnt[r[i] + 1]--;
g[l[i]].emplace_back(r[i] + 1 + n, i);
g[l[i] + n].emplace_back(2 * n, i);
}
for(int i = 0; i < n; i ++) {
cnt[i + 1] += cnt[i];
if(cnt[i] < 2) return cout << "impossible\n", 0;
if(cnt[i] > 2) {
g[i + 1].emplace_back(i, 0);
g[i + 1 + n].emplace_back(i + n, 0);
}
}
for(int i = 0; i < n; i ++) {
tim ++;
if (dfs(i, i + n)) {
memset(cnt, 0, sizeof cnt);
for(int i : path) cnt[i] = 1;
for(int i = 1; i <= m; i++) cout << cnt[i];
return 0;
}
}
cout << "impossible\n";
}
