#include <iostream>
#include <vector>
#include <algorithm>
#include <cassert>
#include <random>
using ll = long long;
#define debug(x) #x << " = " << x << '\n'
const int NMAX = 1000;
std::vector<int> g[NMAX];
bool vis[NMAX];
bool color[NMAX];
void add_edge(int u, int v) {
g[u].push_back(v);
g[v].push_back(u);
}
bool bipartite = true;
void dfs(int u) {
vis[u] = true;
for (const auto &v : g[u]) {
if (!vis[v]) {
color[v] = 1 ^ color[u];
dfs(v);
} else {
if (color[u] == color[v]) {
bipartite = false;
}
}
}
}
std::mt19937 rng(123);
int main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
#endif
std::ios_base::sync_with_stdio(false);
std::cin.tie(0);
int n, m;
std::cin >> n >> m;
std::vector<std::pair<int, int>> a(m);
for (auto &[l, r] : a) {
std::cin >> l >> r;
l--, r--;
}
std::vector<std::vector<int>> active(n);
for (int i = 0; i < m; i++) {
auto [l, r] = a[i];
if (l <= r) {
for (int j = l; j <= r; j++) {
active[j].push_back(i);
}
} else {
for (int j = l; j < n; j++) {
active[j].push_back(i);
}
for (int j = 0; j <= r; j++) {
active[j].push_back(i);
}
}
}
for (int i = 0; i < n; i++) {
if ((int) active[i].size() <= 1) {
std::cout << "impossible";
return 0;
} else if ((int) active[i].size() == 2) {
add_edge(active[i][0], active[i][1]);
}
}
for (int i = 0; i < m; i++) {
if (!vis[i] && !g[i].empty()) {
dfs(i);
}
}
if (!bipartite) {
std::cout << "impossible";
} else {
std::vector<int> taken(n, 0);
auto add_colored = [&](int l, int r, int c) {
if (l <= r) {
for (int i = l; i <= r; i++) {
taken[i] |= (1 << c);
}
} else {
for (int i = l; i < n; i++) {
taken[i] |= (1 << c);
}
for (int i = 0; i <= r; i++) {
taken[i] |= (1 << c);
}
}
};
std::vector<int> order(m);
for (int i = 0; i < m; i++) {
order[i] = i;
}
for (int repeat = 0; repeat < 10; repeat++) {
std::shuffle(order.begin(), order.end(), rng);
for (int i = 0; i < m; i++) {
if (vis[i]) {
add_colored(a[i].first, a[i].second, color[i]);
}
}
for (const auto &i : order) {
if (!vis[i]) {
auto [l, r] = a[i];
int become = 0;
if (l <= r) {
for (int j = l; j <= r; j++) {
become |= (3 ^ taken[j]);
}
} else {
for (int j = r; j < n; j++) {
become |= (3 ^ taken[j]);
}
for (int j = 0; j <= l; j++) {
become |= (3 ^ taken[j]);
}
}
if (become & 1) {
color[i] = 0;
} else {
color[i] = 1;
}
add_colored(l, r, color[i]);
}
}
if (std::count(taken.begin(), taken.end(), 3) == n) {
for (int i = 0; i < m; i++) {
std::cout << color[i];
}
return 0;
}
}
}
return 0;
}
