#include <bits/stdc++.h>
using namespace std;
#define lli long long int
#define X first
#define Y second
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define pii pair<int, int>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define test(args...) abc("[" + string(#args) + "]", args)
void abc() {cerr << endl;}
template <typename T, typename ...U> void abc(T a, U ...b) {
cerr << a << ' ', abc(b...);
}
template <typename T> void printv(T l, T r) {
while (l != r) cout << *l << " \n"[++l == r];
}
const int mod = 1e9 + 7, N = 200000;
int main () {
ios::sync_with_stdio(false);
cin.tie(0);
int n, m;
cin >> n >> m;
vector <pii> a(m);
int mx1 = 0, mx2 = 0;
for (int i = 0; i < m; ++i) cin >> a[i].X >> a[i].Y, --a[i].X;
vector <int> ans(m, 0);
vector <int> p(m);
iota(all(p), 0);
sort(all(p), [&](int i, int j) {
return a[i].X < a[j].X;
});
for (int i : p) {
if (mx1 < a[i].X || mx2 < a[i].X) break;
if (mx1 < mx2) {
mx1 = max(mx1, a[i].Y);
} else {
mx2 = max(mx2, a[i].Y);
ans[i] = 1;
}
}
if (mx1 < n || mx2 < n) return cout << "impossible\n", 0;
for (int i : ans) cout << i;
cout << endl;
}
