#include<bits/stdc++.h>
using namespace std;
#define FOR(i, a, b) for(int i = a; i < b; ++i)
#define REP(i, n) FOR(i, 0, n)
#define _ << " " <<
#define sz(x) ((int) x.size())
#define pb(x) push_back(x)
#define TRACE(x) cerr << #x << " = " << x << endl
typedef long long ll;
typedef pair<int, int> point;
const int MAXN = 2e5 + 5, off = 1 << 18;
struct event{
int x = -1, y = -1, id = -1;
event(){}
event(int x, int y, int id) : x(x), y(y), id(id) {}
friend bool operator < (const event &A, const event &B){
if(A.x != B.x) return A.x < B.x;
return A.y > B.y;
}
};
int n, m, par[MAXN];
event rail[MAXN];
vector <event> v, ev;
vector <int> djeca[MAXN];
bool sol[MAXN];
struct Tournament{
int t[2 * off], p[2 * off];
Tournament(){}
void reset(){
memset(t, 0, sizeof(t));
memset(p, -1, sizeof(p));
}
void prop(int x, int lo, int hi){
if(p[x] == -1)
return;
t[x] = p[x] * (hi - lo);
if(x < off){
p[x * 2] = p[x];
p[x * 2 + 1] = p[x];
}
p[x] = -1;
}
void update(int x, int lo, int hi, int a, int b, int val){
prop(x, lo, hi);
if(lo >= b || hi <= a) return;
if(lo >= a && hi <= b) { p[x] = val; prop(x, lo, hi); return; }
int mid = (lo + hi) >> 1;
update(x * 2, lo, mid, a, b, val); update(x * 2 + 1, mid, hi, a, b, val);
t[x] = t[x * 2] + t[x * 2 + 1];
}
int get(int x, int lo, int hi, int a, int b){
prop(x, lo, hi);
if(lo >= b || hi <= a) return 0;
if(lo >= a && hi <= b) return t[x];
int mid = (lo + hi) >> 1;
return get(x * 2, lo, mid, a, b) +
get(x * 2 + 1, mid, hi, a, b);
}
} T;
bool check(int x){
T.reset();
REP(i, m){
if(sol[i] == x){
if(rail[i].x > rail[i].y){
T.update(1, 0, off, rail[i].x, n + 1, 1);
T.update(1, 0, off, 1, rail[i].y + 1, 1);
}
else{
T.update(1, 0, off, rail[i].x, rail[i].y + 1, 1);
}
}
}
if(T.get(1, 0, off, 1, n + 1) == n)
return true;
else
return false;
}
void ubaci(int x, int y){
if(x > y){
T.update(1, 0, off, x, n + 1, 1);
T.update(1, 0, off, 1, y + 1, 1);
}
else{
T.update(1, 0, off, x, y + 1, 1);
}
}
void izbaci(int x, int y){
if(x > y){
T.update(1, 0, off, x, n + 1, 0);
T.update(1, 0, off, 1, y + 1, 0);
}
else{
T.update(1, 0, off, x, y + 1, 0);
}
}
bool provjeri(event A){
if(A.x > A.y){
if(T.get(1, 0, off, A.x, n + 1) != n - A.x + 1)
return false;
if(T.get(1, 0, off, 1, A.y + 1) != A.y)
return false;
}
else{
if(T.get(1, 0, off, A.x, A.y + 1) != A.y - A.x + 1)
return false;
}
return true;
}
bool moze(event A, event B, event C, event D){
// A i B moraju bit pokriveni sa C i D
ubaci(C.x, C.y); ubaci(D.x, D.y);
for(auto it : djeca[A.id])
ubaci(rail[it].x, rail[it].y);
for(auto it : djeca[B.id])
ubaci(rail[it].x, rail[it].y);
bool ret;
if(provjeri(A) && provjeri(B))
ret = true;
else
ret = false;
izbaci(C.x, C.y); izbaci(D.x, D.y);
for(auto it : djeca[A.id])
izbaci(rail[it].x, rail[it].y);
for(auto it : djeca[B.id])
izbaci(rail[it].x, rail[it].y);
return ret;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
memset(par, -1, sizeof(par));
cin >> n >> m;
REP(i, m){
int a, b; cin >> a >> b;
rail[i] = event(a, b, i);
if(a <= b)
v.pb(event(a, b, i));
if(a > b)
v.pb(event(a, b + n, i));
else
v.pb(event(a + n, b + n, i));
}
sort(v.begin(), v.end());
event curr = v[0];
FOR(i, 1, sz(v)){
if(curr.x <= v[i].x && curr.y >= v[i].y){
par[ v[i].id ] = curr.id;
}
if(curr.y < v[i].y)
curr = v[i];
}
REP(i, m)
if(par[i] == i || par[i] == -1)
ev.pb(rail[i]);
sort(ev.begin(), ev.end());
T.reset();
for(int i = 0; i < sz(ev); i += 2)
sol[ ev[i].id ] = true;
REP(i, m){
if(par[i] != i && par[i] != -1){
djeca[ par[i] ].pb(i);
sol[i] = !sol[ par[i] ] ;
}
}
if(sz(ev) % 2 == 0){
if(check(0) && check(1))
REP(i, m)
cout << sol[i];
else{
cout << "impossible";
}
}
else{
REP(i, m)
sol[i] = 0;
REP(i, sz(ev)){
if(moze( ev[(i + 1) % sz(ev)], ev[(i + 2) % sz(ev)], ev[(i) % sz(ev)], ev[(i + 3) % sz(ev)] )){
for(int j = (i + 1) % sz(ev); j >= 0; j -= 2)
sol[ ev[j].id ] = 1;
for(int j = (i + 2) % sz(ev); j < sz(ev); j += 2)
sol[ ev[j].id ] = 1;
REP(j, m)
if(par[j] != j && par[j] != -1)
sol[j] = !sol[par[j]];
if(check(0) && check(1))
REP(j, m)
cout << sol[j];
else
cout << "impossible";
return 0;
}
}
cout << "impossible";
}
}
