/*input
5 4
1 3
2 4
4 5
5 1
*/
#include <iostream>
#include <vector>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <cassert>
#include <algorithm>
#include <cstdlib>
#include <numeric>
#include <climits>
#include <fstream>
using namespace std;
#define FOR(i, a, b) for (int i = a; i <= b; ++i)
#define FORA(i, a) for (auto &i : a)
#define FORB(i, a, b) for (int i = a; i >= b; --i)
#define SZ(a) ((int) a.size())
#define ALL(a) begin(a), end(a)
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vl;
#define fi first
#define se second
// start of code
struct Seg
{
int l, r, i;
bool operator< (const Seg &s) const
{
return (l == s.l ? r > s.r : l < s.l);
}
};
const int MAXN = 200007;
int N, M;
int cover[MAXN], par[MAXN], newIdx[MAXN], cnt, tmp, ptr;
vector<Seg> segs, segs1;
bool color[MAXN];
void addCover(Seg s, int _N = N)
{
assert(s.l <= _N);
if (s.r <= _N) {
++ cover[s.l];
-- cover[s.r + 1];
} else {
++ cover[s.l];
-- cover[_N + 1];
++ cover[1];
-- cover[s.r - _N + 1];
}
}
signed main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
// read
cin >> N >> M;
segs.resize(M);
for (int i = 0; i < M; ++i) {
cin >> segs[i].l >> segs[i].r;
if (segs[i].l > segs[i].r) segs[i].r += N;
segs[i].i = i;
par[i] = -1;
}
// re-organize
ptr = 0;
for (int i = 1; i < M; ++i) {
if (segs[i].r - segs[i].l > segs[ptr].r - segs[ptr].l) {
ptr = i;
}
}
int shiftBack = segs[ptr].l - 1;
for (int i = 0; i < M; ++i) {
segs[i].l -= shiftBack, segs[i].r -= shiftBack;
if (segs[i].l <= 0) segs[i].l += N, segs[i].r += N;
}
// sort
sort(segs.begin(), segs.end());
// cout << "-1-" << endl;
// for (Seg &s : segs) cout << s.l << ' ' << s.r << ": " << s.i << endl;
// cout << "--" << endl;
// remove interiors
for (int i = 1; i <= N; ++i) cover[i] = 0;
int ptr = 0; segs1.push_back(segs[0]);
for (int i = 1; i < M; ++i) {
if (segs[i].r <= segs[ptr].r) {
par[segs[i].i] = segs[ptr].i;
addCover(segs[i]);
} else {
ptr = i;
segs1.push_back(segs[i]);
}
}
segs1.swap(segs); segs1.clear();
// calculate
for (int i = 1; i <= N; ++i) {
cover[i] += cover[i - 1];
newIdx[i] = newIdx[i - 1];
if (!cover[i]) ++newIdx[i];
}
int N2 = newIdx[N];
for (int i = 1; i <= N; ++i) {
newIdx[i + N] = newIdx[i] + N2;
}
// cout << "-2-" << endl;
// for (Seg &s : segs) cout << s.l << ' ' << s.r << ": " << s.i << endl;
// cout << "--" << endl;
// for (int i = 1; i <= N; ++i) cout << cover[i]; cout << endl;
for (Seg &s : segs) {
s.l = newIdx[s.l - 1] + 1;
s.r = newIdx[s.r];
if (s.l > N2) s.l -= N2, s.r -= N2;
if (s.l <= s.r) segs1.push_back(s);
}
// cout << "-3-" << endl;
// for (Seg &s : segs1) cout << s.l << ' ' << s.r << ": " << s.i << endl;
// cout << "--" << endl;
for (int i = 1; i <= N; ++i) cover[i] = 0;
for (Seg &s : segs1) addCover(s, N2);
for (int i = 1; i <= N2; ++i) cover[i] += cover[i - 1];
// check
for (int i = 1; i <= N2; ++i) {
if (cover[i] <= 1) return cout << "impossible\n", 0;
}
if (segs1.size() & 1) {
if (segs1.size() == 1) return cout << "impossible\n", 0;
bool flag = 0;
for (int i = 0; i < (int) segs1.size() && !flag; ++i) {
Seg sl = segs1[i - 2 < 0 ? i - 2 + segs1.size() : i - 2];
Seg sm1 = segs1[i - 1 < 0 ? i - 1 + segs1.size() : i - 1];
Seg sm2 = segs1[i];
Seg sr = segs1[i + 1 >= (int) segs1.size() ? i + 1 - segs1.size() : i + 1];
if (sm1.l < sl.l) sm1.l += N2, sm1.r += N2;
if (sm2.l < sm1.l) sm2.l += N2, sm2.r += N2;
if (sr.l < sm2.l) sr.l += N2, sr.r += N2;
if (sl.r + 1 >= sr.l) {
rotate(segs1.begin(), segs1.begin() + i, segs1.end());
flag = 1;
// cout << "-4-" << ' ' << i << endl;
// for (Seg &s : segs1) cout << s.l << ' ' << s.r << ": " << s.i << endl;
// cout << "--" << endl;
}
}
if (!flag) return cout << "impossible\n", 0;
}
for (int i = 0; i < (int) segs1.size(); ++i) {
color[segs1[i].i] = i & 1;
}
for (int i = 0; i < M; ++i) {
if (par[i] >= 0) {
color[i] = !color[par[i]];
}
cout << color[i];
}
cout << endl;
return 0;
}
