//edi subtask 4
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
const ll maxn = 1e5+5;
ll N,M,a[maxn],b[maxn];
vector<pair<ll,ll>> pr[maxn];
ll ans[maxn];
int main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> N >> M;
for(int i=0;i<M;i++) cin >> a[i] >> b[i];
for(int i=0;i<M;i++) pr[a[i]].push_back({b[i],i});
for(int i=1;i<=N;i++) sort(pr[i].begin(),pr[i].end());
ll cur1 = 1,cur2 = 1;
for(int i=1;i<=N;i++){
if(min(cur1,cur2)<i){
cout << "impossible";
return 0;
}
for(pair<ll,ll> j:pr[i]){
if(cur1<=cur2){
cur1 = max(cur1,j.first+1);
ans[j.second] = 0;
}
else{
cur2 = max(cur2,j.first+1);
ans[j.second] = 1;
}
}
}
if(min(cur1,cur2)<=N){
cout << "impossible";
return 0;
}
for(int i=0;i<M;i++) cout << ans[i];
}
