#include <bits/stdc++.h>
using namespace std;
int N, M, X[100005], Y[100005];
int R[100005], ST[400005], lazy[400005];
vector<int> adj[100005];
void prop(int v, int l, int r) {
if(l == r || !lazy[v]) return;
lazy[v * 2] += lazy[v];
lazy[v * 2 + 1] += lazy[v];
ST[v * 2] += lazy[v];
ST[v * 2 + 1] += lazy[v];
lazy[v] = 0;
return;
}
void update(int v, int l, int r, int lo, int hi, int val) {
prop(v, l, r);
if(l > hi || r < lo) return;
if(l >= lo && r <= hi) {
ST[v] += val; lazy[v] += val;
prop(v, l, r); return;
}
update(v * 2, l, (l + r) / 2, lo, hi, val);
update(v * 2 + 1, (l + r) / 2 + 1, r, lo, hi, val);
ST[v] = min(ST[v * 2], ST[v * 2 + 1]);
}
int query(int v, int l, int r, int lo, int hi) {
prop(v, l, r);
if(l > hi || r < lo) return 1000000007;
if(l >= lo && r <= hi) return ST[v];
return min(query(v * 2, l, (l + r) / 2, lo, hi),
query(v * 2 + 1, (l + r) / 2 + 1, r, lo, hi));
}
bool dfs(int v) {
for(auto u : adj[v]) {
if(R[u] == 0) {
R[u] = -R[v];
if(dfs(u)) return true;
}
else if(R[u] == R[v]) return true;
}
return false;
}
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cin >> N >> M; int K = 0; set<int> S;
vector<pair<int, int>> P;
for(int l = 0; l < M; l++) {
cin >> X[l] >> Y[l]; X[l]--, Y[l]--;
if(X[l] > Y[l]) S.insert(l);
P.push_back({X[l], -l - 1});
P.push_back({Y[l], l});
}
sort(P.begin(), P.end());
for(int l = 0; l < N; l++) {
while(K < P.size() && P[K] < make_pair(l, 0)) {
if(P[K].second < 0) S.insert(-P[K].second - 1);
else S.erase(P[K].second);
K++;
}
if(S.size() < 2) { cout << "impossible\n"; return 0; }
if(S.size() == 2) {
int U = *S.begin();
int V = *next(S.begin());
adj[U].push_back(V);
adj[V].push_back(U);
}
}
for(int l = 0; l < M; l++) {
if(R[l] == 0 && adj[l].size() > 0) {
R[l] = -1;
if(dfs(l)) { cout << "impossible\n"; return 0; }
}
}
for(int l = 0; l < M; l++) {
if(R[l] >= 0) {
if(X[l] <= Y[l])
update(1, 0, N - 1, X[l], Y[l], 1);
else update(1, 0, N - 1, 0, Y[l], 1),
update(1, 0, N - 1, X[l], N - 1, 1);
}
}
for(int l = 0; l < M; l++) {
if(!R[l]) {
int T = 1000000007;
if(X[l] <= Y[l])
T = query(1, 0, N - 1, X[l], Y[l]);
else T = min(query(1, 0, N - 1, 0, Y[l]),
query(1, 0, N - 1, X[l], N - 1));
if(T <= 1) R[l] = 1;
else {
R[l] = -1;
if(X[l] <= Y[l])
update(1, 0, N - 1, X[l], Y[l], -1);
else update(1, 0, N - 1, 0, Y[l], -1),
update(1, 0, N - 1, X[l], N - 1, -1);
}
}
}
for(int l = 0; l < M; l++)
cout << (R[l] == -1 ? 0 : 1);
}
