#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 = 100000;
int main () {
srand(time(NULL));
ios::sync_with_stdio(false);
cin.tie(0);
int n, m;
cin >> n >> m;
vector <pii> a(m);
for (int i = 0; i < m; ++i) cin >> a[i].X >> a[i].Y, --a[i].X;
double t = 1000;
vector <int> p(m);
iota(all(p), 0);
while (t--) {
random_shuffle(all(p));
vector <vector <bool>> is(n, vector <bool> (2, false));
vector <int> ans(m, 0);
int now = 0;
for (int i : p) {
ans[i] = now;
int l, r;
tie(l, r) = a[i];
if (l < r) {
for (int j = l; j < r; ++j) is[j][now] = true;
} else {
for (int j = l; j < n; ++j) is[j][now] = true;
for (int j = 0; j < r; ++j) is[j][now] = true;
}
bool ok = true;
for (int j = 0; j < n; ++j) ok &= is[j][now];
if (ok) {
if (now == 1) {
for (int i : ans) cout << i;
cout << endl;
return 0;
}
now++;
}
}
}
cout << "impossible\n";
}
