#include<bits/stdc++.h>
#define fr first
#define sc second
using namespace std;
const int N = 200010;
struct Segtree{
pair <int, int> tree[4*N]; int lazy[4*N];
pair <int, int> join(pair <int, int> a, pair <int, int> b){
if(a.fr < b.fr) return a;
else if(b.fr < a.fr) return b;
if(a.sc < b.sc) return a;
return b;
}
void unlazy(int node, int l, int r){
if(lazy[node] == 0) return;
tree[node].first = lazy[node];
tree[node].second = l;
if(l != r){
lazy[2*node] = lazy[node];
lazy[2*node+1] = lazy[node];
}
lazy[node] = 0;
}
void build(int node, int l,int r){
lazy[node] = 0;
if(l == r){
tree[node] = {0, l};
return;
}
int mid = (l+r)/2;
build(2*node, l, mid);
build(2*node+1, mid+1, r);
tree[node] = join(tree[2*node], tree[2*node+1]);
return;
}
void update(int node, int l, int r, int tl, int tr, int val){
unlazy(node, tl, tr);
if(l > tr or tl > r) return;
if(l <= tl and tr <= r){
lazy[node] = val;
unlazy(node, tl, tr);
return;
}
int mid = (tl+tr)/2;
update(2*node, l, r, tl, mid, val);
update(2*node+1, l, r, mid+1,tr, val);
tree[node] = join(tree[2*node], tree[2*node+1]);
return;
}
pair <int, int> query(int node, int l, int r, int tl, int tr){
unlazy(node, tl, tr);
if(l > tr or tl > r) return {2, 0};
if(l <= tl and tr <= r) return tree[node];
int mid = (tl+tr)/2;
return join(query(2*node, l, r, tl, mid), query(2*node+1, l, r, mid+1, tr));
}
} seg[2];
vector <array <int, 3>> intervalos;
int res[N];
int main(){
int n, m;
cin >> n >> m;
for(int i = 1;i <= m;i++){
int a, b;
cin >> a >> b;
intervalos.push_back({a, -b, i-1});
}
sort(intervalos.begin(), intervalos.end());
for(int i = 0;i < m;i++){
intervalos[i][1] *= -1;
}
seg[0].build(1, 1, n);
seg[1].build(1, 1, n);
for(int i = 0;i < m;i++){
auto [l, r, _] = intervalos[i];
pair <int, int> a = seg[0].query(1, l, r, 1, n);
pair <int, int> b = seg[1].query(1, l, r, 1, n);
if(a.fr == 1 and b.fr == 1){
res[_] = 0;
continue;
}
else if(a.fr == 1 and b.fr == 0){
res[_] = 1;
seg[1].update(1, l, r, 1, n, 1);
}
else if(a.fr == 0 and b.fr == 1){
res[_] = 0;
seg[0].update(1, l, r, 1, n, 1);
}
else{
if(a.sc < b.sc){
res[_] = 0;
seg[0].update(1, l, r, 1, n, 1);
}
else{
res[_] = 1;
seg[1].update(1, l, r, 1, n, 1);
}
}
}
if(seg[0].query(1, 1, n, 1, n).fr != 1 or seg[1].query(1, 1, n, 1, n).sc != 1){
cout << "impossible\n";
return 0;
}
for(int i = 0;i < m;i++){
cout << res[i];
}
cout << '\n';
}
