10 20 10 5
 20 1 2 3
 7 2 2 2
 25 10 5 10
 999 999 899 299
 10000 5000 0 5000
 2 2 2 2
 1 0 2 0
 3 3 2 1
 1 1 0 0
 1 0 0 1
 20 10 20 30
 505 142 321 12
 101 10 10 50
 10 19 15 100
 10000 5000 5000 0
 1234 645 876 1000
 3 10 10 10
 1 0 1 0
 7 3 0 5
 101 10 0 50
 1 0 0 0
 10 0 8 10
 1 2 0 0
 5 2 1 1
 8765 2432 2789 4993
 8987 4000 2534 4534
 10000 5000 5000 5000
 10000 5000 2500 2500
 10000 0 5000 5000
 10000 4999 2500 2500
 5 5000 5000 5000
 10000 4534 2345 4231
 5643 1524 1423 2111
 7777 4444 3333 2222
 2500 5000 5000 5000
 10000 2500 2500 2500
 5000 5000 5000 5000

36
 0
 1
 12
 145000
 1251
 3
 1
 3
 0
 0
 57
 0
 33
 35
 0
 141636
 6
 1
 1
 3
 0
 5
 1
 0
 1697715
 2536267
 6253751
 1
 2501
 0
 12
 2069003
 146687
 1236544
 1565001
 0
 4691251

#include <bits/stdc++.h>
using namespace std;
signed main() {
  vector<pair<long long int, long long int> > v;
  long long int n, m, a, b, k, z, cnt = 0, q, f = 0;
  cin >> n >> m;
  for (long long int i = 0; i < m; i++) {
    cin >> a >> b;
    v.push_back({a, b});
  }
  for (long long int i = 0; i < m - 1; i++) {
    if (v[i + 1].first == v[i].second) {
      cnt = 2;
      f = 1;
      k = v[i].second;
      z = i;
      while (z < m) {
        z++;
        if (v[z + 1].first == k) cnt++;
      }
      cout << k << " " << cnt;
      break;
    } else if ((v[i + 1].first - v[i].second) > 1) {
      f = 1;
      cout << v[i].second + 1 << " " << 0;
      break;
    }
  }
  if (f == 0) {
    if (v[m - 1].second < m)
      cout << v[m - 1].second;
    else if (f == 0)
      cout << "OK";
  }
}
