#include"bits/stdc++.h"
using namespace std;
int N, M, x, y, Cnt[200005], D[100005];
int Two[100005], T, Vt[100005][2], V[100005];
vector<int> AdjList[100005];
int NT[100005], AC[100005], last[2];
pair<int, int> P[100005];
class Cmp {
public:
bool operator() (int i, int j) const {
return P[i] < P[j];
}
};
bool bipartite(int u) {
queue<int> Q;
Q.push(u);
while (!Q.empty()) {
u = Q.front(), Q.pop();
for (int v : AdjList[u]) {
if (!NT[v]) continue;
if (AC[v] == AC[u]) return false;
if (AC[v]) continue;
Q.push(v), AC[v] = -AC[u];
}
}
return true;
}
int main() {
scanf("%d%d", &N, &M);
for (int i = 1; i <= M; i++) {
scanf("%d%d", &x, &y);
if (y < x) y += N;
++Cnt[--x], --Cnt[y];
P[i] = {x, y};
D[i-1] = i;
}
for (int i = 1; i < 2*N; i++)
Cnt[i] += Cnt[i-1];
for (int i = 0; i < N; i++) {
Cnt[i] += Cnt[i+N];
//printf("Cnt[%d]: %d\n", i, Cnt[i]);
if (Cnt[i] < 2) {
printf("impossible");
return 0;
}
if (Cnt[i] == 2) Two[T++] = i;
}
if (T > 0) {
for (int i = 1; i <= M; i++) {
tie(x, y) = P[i];
int lb = (lower_bound(Two, Two + T, x) - Two) % T;
int ub = (lower_bound(Two, Two + T, y % N) - Two) % T;
//printf("(%d, %d) [%d, %d]\n", x, y, lb, ub);
for (int j = lb; j != ub; j = (j + 1) % T)
Vt[j][V[j]++] = i;
}
//for (int i = 0; i < T; i++) printf("[%d] %d %d\n", V[i], Vt[i][0], Vt[i][1]);
for (int i = 0; i < T; i++) {
AdjList[Vt[i][0]].push_back(Vt[i][1]);
AdjList[Vt[i][1]].push_back(Vt[i][0]);
NT[Vt[i][0]] = NT[Vt[i][1]] = 1;
}
//for (int i = 1; i <= M; i++) printf("%d ", NT[i]); printf("\n");
}
sort(D, D + M, Cmp());
last[0] = last[1] = P[D[0]].first;
for (int i = 0; i < M; i++) {
int p = D[i];
tie(x, y) = P[p];
if (AC[p]) {
int l = (AC[p] + 1) >> 1;
last[l] = max(last[l], y);
continue;
}
int l = last[0] < last[1] ? 0 : 1;
AC[p] = l - !l;
if (NT[p] && !bipartite(p)) {
printf("impossible");
return 0;
}
last[l] = max(last[l], y);
//for (int m = 1; m <= M; m++) AC[m] ? printf("%d", (AC[m]+1) >> 1) : printf("-"); printf("\n");
}
for (int i = 1; i <= M; i++)
printf("%d", 1 - ((AC[i] + 1) >> 1));
}
/*
12 4
1 9
4 12
7 3
10 6
*/
