#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;
int vis[N * 2], timer;
bool dfs(int u, int p)
{
if(u == p)
return 1;
if(vis[u] == timer)
return 0;
vis[u] = timer;
for(auto e : adj[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()
{
ios_base::sync_with_stdio(0);
cin.tie(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);
adj[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", 0;
if(cnt[i] > 2)
{
adj[i + 1].emplace_back(i, 0);
adj[i + 1 + n].emplace_back(i + n, 0);
}
}
for(int i = 0; i < n; i ++)
{
timer ++;
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";
}
