#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;
vector <int> ans, adj[N];
struct Seg {
int l, r, m;
vector <int> unknown;
int one = 0, zero = 0;
Seg* ch[2];
Seg (int _l, int _r) : l(_l), r(_r), m(l + r >> 1) {
if (r - l > 1) {
ch[0] = new Seg(l, m);
ch[1] = new Seg(m, r);
}
}
void add(int a, int b, int id, int x) {
if (a <= l && r <= b) {
if (x == -1) unknown.pb(id);
if (x == 0) zero++;
if (x == 1) one++;
} else {
if (a < m) ch[0]->add(a, b, id, x);
if (m < b) ch[1]->add(a, b, id, x);
}
}
int query(int p) {
if (r - l == 1) return unknown.size();
return ch[p >= m]->query(p) + unknown.size();
}
vector <int> get(int p) {
if (r - l == 1) return unknown;
vector <int> a = unknown, b = ch[p >= m]->get(p);
for (int i : b) a.pb(i);
return a;
}
int val() {return (zero ? 1 : 0) + (one ? 2 : 0);}
int get2(int p) {
if (r - l == 1) return val();
return val() | ch[p >= m]->get2(p);
}
int get_unknown(int p) {
while (!unknown.empty()) {
int v = unknown.back(); unknown.pop_back();
if (ans[v] == -1) return v;
}
return ch[p >= m]->get_unknown(p);
}
};
int main () {
ios::sync_with_stdio(false);
cin.tie(0);
int n, m;
cin >> n >> m;
vector <pii> a(m);
Seg root(0, n);
for (int i = 0, l, r; i < m; ++i) {
cin >> a[i].X >> a[i].Y, --a[i].X;
tie(l, r) = a[i];
if (l < r) {
root.add(l, r, i, -1);
} else {
root.add(l, n, i, -1);
root.add(0, r, i, -1);
}
}
for (int i = 0; i < n; ++i) {
if (root.query(i) < 2) return cout << "impossible\n", 0;
if (root.query(i) == 2) {
vector <int> tmp = root.get(i);
adj[tmp[0]].pb(tmp[1]), adj[tmp[1]].pb(tmp[0]);
}
}
auto chg = [&](int i, int x) {
ans[i] = x;
int l, r;
tie(l, r) = a[i];
if (l < r) {
root.add(l, r, i, x);
} else {
root.add(l, n, i, x);
root.add(0, r, i, x);
}
};
ans.assign(m, -1);
bool odd_cycle = false;
function<void(int)> dfs = [&](int v) {
for (int u : adj[v]) {
if (ans[u] == -1) {
chg(u, ans[v] ^ 1);
dfs(u);
} else if (ans[v] == ans[u]) {
odd_cycle = true;
}
}
};
for (int i = 0; i < m; ++i) if (ans[i] == -1 && !adj[i].empty()) {
chg(i, 0);
dfs(i);
}
if (odd_cycle) return cout << "impossible\n", 0;
for (int i = 0; i < n; ++i) {
int ok = root.get2(i);
if (~ok & 1) {
int p = root.get_unknown(i);
chg(p, 0);
}
if (~ok & 2) {
int p = root.get_unknown(i);
chg(p, 1);
}
}
for (int i : ans) {
cout << (i == -1 ? 0 : i);
}
cout << endl;
}
