#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr ll INF = (ll)1e18;
constexpr ll MOD = (ll)1e9 + 7;
constexpr double EPS = 1e-9;
constexpr ll dx[4] = {1LL, 0LL, -1LL, 0LL};
constexpr ll dy[4] = {0LL, 1LL, 0LL, -1LL};
constexpr ll dx8[8] = {1LL, 0LL, -1LL, 0LL, 1LL, 1LL, -1LL, -1LL};
constexpr ll dy8[8] = {0LL, 1LL, 0LL, -1LL, 1LL, -1LL, 1LL, -1LL};
void p() { std::cout << '\n'; }
template <typename Head, typename... Tail>
void p(Head head, Tail... tail) {
  std::cout << head << (sizeof...(tail) ? " " : "");
  p(tail...);
}
template <typename T>
inline void pv(std::vector<T>& v) {
  for (ll i = 0, N = v.size(); i < N; i++)
    std::cout << v[i] << " \n"[i == N - 1];
}
template <typename T>
inline T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <typename T>
inline T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
template <typename T>
inline bool chmax(T& a, T b) {
  return a < b && (a = b, true);
}
template <typename T>
inline bool chmin(T& a, T b) {
  return a > b && (a = b, true);
}
template <typename T>
inline void uniq(std::vector<T>& v) {
  v.erase(std::unique(v.begin(), v.end()), v.end());
}
constexpr ll N_MAX = 3;
constexpr ll M_MAX = 5;
constexpr ll C_I_MAX = 9;
ll N, M;
vector<ll> s;
vector<ll> c;
void solve() {
  scanf("%lld%lld", &N, &M);
  s.assign(M, 0);
  c.assign(M, 0);
  for (ll i = 0, i_length = (M); i < i_length; ++i) {
    scanf("%lld%lld", &s[i], &c[i]);
    s[i]--;
  }
  ll x = pow(10, N - 1);
  for (; x < pow(10, N); x++) {
    string t = to_string(x);
    bool ok = true;
    for (ll i = 0, i_length = (M); i < i_length; ++i) {
      if (t[s[i]] - '0' != c[i]) {
        ok = false;
      }
    }
    do {
    } while (false);
    if (ok) {
      p(x);
      return;
    }
  }
  exit(1);
}
signed main() {
  solve();
  return 0;
}
