#include <bits/stdc++.h>
using namespace std;
bool sortbysec(const pair<int, int> &a, const pair<int, int> &b) {
  if (a.second < b.second) return true;
  if (a.second == b.second) return a.first < b.first;
  return false;
}
bool isprime(int n) {
  if (n <= 1) return false;
  for (int i = 2; i <= sqrt(n); i++)
    if (n % i == 0) return false;
  return true;
}
bool isPowerOfTwo(int n) {
  if (n == 0) return false;
  return (ceil(log2(n)) == floor(log2(n)));
}
int gcd(int a, int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long int lcm(long long int a, long long int b) {
  return (a / gcd(a, b)) * b;
}
long long int ncr(long long int n, long long int r) {
  if (r == 0) return 1;
  r = min(r, n - r);
  long long int ans = 1;
  for (int i = 1; i <= r; i++) {
    ans *= (n - i + 1);
    ans /= i;
  }
  return ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int t = 1;
  while (t--) {
    int n, m;
    cin >> n >> m;
    vector<pair<int, int>> v;
    int x, y;
    for (int i = 0; i < m; i++) {
      cin >> x >> y;
      v.push_back(make_pair(x, y));
    }
    int ans = 0;
    if (v[0].first != 1) {
      cout << 1 << " " << 0 << "\n";
    } else {
      int dayno = -1;
      for (int i = 1; i < v.size(); i++) {
        if (v[i].first == v[i - 1].second) {
          ans = 2;
          dayno = v[i].first;
          int j = i + 1;
          while (j < v.size() && v[j].first == v[i].first) ans++, j++;
          break;
        } else if (v[i].first != v[i - 1].second + 1) {
          dayno = v[i - 1].second + 1;
          ans = 0;
          break;
        }
      }
      if (dayno != -1)
        cout << dayno << " " << ans << "\n";
      else {
        if (v[v.size() - 1].second != n)
          cout << v[v.size() - 1].second + 1 << " " << 0 << "\n";
        else
          cout << "OK"
               << "\n";
      }
    }
  }
  return 0;
}
