/*************************************
* 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; }
struct Segment {
int l, r, id;
bool operator < (const Segment &other) const {
return make_pair(l, r) < make_pair(other.l, other.r);
}
};
// end of template
const int MAX = 1e5 + 5;
int N, M;
Segment seg[MAX];
void init(void) {
cin >> N >> M;
REP(i, M) {
cin >> seg[i].l >> seg[i].r;
seg[i].id = i;
}
}
int res[MAX];
namespace SUBTASK_1 {
int sum[2][23];
void solve(void) {
REP(mask, MASK(M)) {
REP(i, 2) memset(sum[i], 0, (N + 1) * sizeof(sum[i]));
REP(i, M) {
int t = BIT(mask, i);
++sum[t][seg[i].l];
--sum[t][seg[i].r + 1];
if (seg[i].l > seg[i].r) ++sum[t][1];
}
bool ok = true;
REP(t, 2) {
FORE(i, 1, N) {
sum[t][i] += sum[t][i - 1];
ok &= !!sum[t][i];
}
}
if (ok) {
REP(i, M) cout << BIT(mask, i);
return;
}
}
cout << "impossible\n";
}
}
void process(void) {
if (max(N, M) <= 20) {
SUBTASK_1 :: solve();
return;
}
sort(seg, seg + M);
int cur[2] = {};
REP(i, M) {
int t = cur[0] > cur[1];
if (seg[i].l > cur[t] + 1) return void(cout << "impossible\n");
maximize(cur[t], seg[i].r);
res[seg[i].id] = t;
}
if (min(cur[0], cur[1]) < N) return void(cout << "impossible\n");
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);
}
