#include <bits/stdc++.h>
using namespace std;
vector<vector<bool>> c(3, vector<bool>(3));
int main() {
  int n, b, c, d;
  cin >> n >> b;
  map<int, int> a;
  for (int i = 0; i < 3; i++) {
    cin >> c >> d;
    if (a.count(c)) {
      if (a.at(c) == d)
        ;
      else {
        cout << "-1";
        return 0;
      }
    }
    a[c] = d;
  }
  if (a.count(1))
    ;
  if (a.at(1) == 0) {
    cout << "-1";
    return 0;
  } else {
    cout << "-1";
    return 0;
  }
  for (int i = 1; i <= n; i++) {
    cout << a[i];
  }
}
