/*************************************
* author: marvinthang *
* created: 05.05.2023 10:12:26 *
*************************************/
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define left ___left
#define right ___right
#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
#define MASK(i) (1LL << (i))
#define BIT(x, i) ((x) >> (i) & 1)
#define __builtin_popcount __builtin_popcountll
#define ALL(v) (v).begin(), (v).end()
#define REP(i, n) for (int i = 0, _n = (n); i < _n; ++i)
#define REPD(i, n) for (int i = (n); i--; )
#define FOR(i, a, b) for (int i = (a), _b = (b); i < _b; ++i)
#define FORD(i, b, a) for (int i = (b), _a = (a); --i >= _a; )
#define FORE(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORDE(i, b, a) for (int i = (b), _a = (a); i >= _a; --i)
#define scan_op(...) istream & operator >> (istream &in, __VA_ARGS__ &u)
#define print_op(...) ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
#include "debug.h"
#else
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
#define DB(...) 23
#define db(...) 23
#define debug(...) 23
#endif
template <class U, class V> scan_op(pair <U, V>) { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>) { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>) { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")"; else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }
template <class A, class B> bool minimize(A &a, B b) { if (a > b) { a = b; return true; } return false; }
template <class A, class B> bool maximize(A &a, B b) { if (a < b) { a = b; return true; } return false; }
// end of template
const int MAX = 3e5 + 5;
int N, M;
int L[MAX], R[MAX];
int cnt[MAX];
void init(void) {
cin >> N >> M;
REP(i, M) {
cin >> L[i] >> R[i];
++cnt[L[i]];
--cnt[R[i] + 1];
if (R[i] < L[i]) {
++cnt[1];
R[i] += N;
}
}
FORE(i, 1, N) {
cnt[i] += cnt[i - 1];
cnt[i + N] = cnt[i + N + N] = cnt[i];
}
}
vector <pair <int, int>> adj[MAX];
int dist[MAX];
pair <int, int> trace[MAX];
bool res[MAX];
void process(void) {
FORE(i, 1, N) if (cnt[i] < 2) return void(cout << "impossible\n");
REP(i, M) {
adj[L[i] - 1].emplace_back(R[i], i);
adj[L[i] + N - 1].emplace_back(R[i] + N, i);
}
int st = -1, len = -1;
REP(i, M) {
int l = R[i] - L[i] + 1;
if (st == -1 || len < l) {
st = i;
len = l;
}
}
memset(dist, 0x3f, sizeof(dist));
deque <int> dq;
dist[R[st]] = 0;
dq.push_back(R[st]);
int e = L[st] + N - 1;
while (!dq.empty()) {
int u = dq.front(); dq.pop_front();
int p = u - 1;
if (p >= L[st] && cnt[u] > 2 && minimize(dist[p], dist[u])) {
dq.push_front(p);
trace[p] = make_pair(u, M);
}
for (auto [v, id]: adj[u]) {
if (v <= R[st] + N && minimize(dist[v], dist[u] + 1)) {
dq.push_back(v);
trace[v] = make_pair(u, id);
}
}
}
if (dist[e] > M) return void(cout << "impossible\n");
res[st] = 1;
while (e != R[st]) {
res[trace[e].se] = 1;
e = trace[e].fi;
}
REP(i, M) cout << res[i];
}
int main(void) {
ios_base::sync_with_stdio(false); cin.tie(nullptr); // cout.tie(nullptr);
file("B");
init();
process();
cerr << "Time elapsed: " << TIME << " s.\n";
return (0^0);
}
