#include <bits/stdc++.h>   using namespace std;   const int inf = 1 << 28;   const double INF = 1e12, EPS = 1e-9;   int n, m, c[101];   void run() {     cin >> n >> m;     for (int i = 0; i < m; i++) {       int a, b;       cin >> a >> b;       for (; a <= b; a++) c[a]++;     }     for (int i = 1; i <= n; i++)       if (c[i] != 1) {         cout << i <<     << c[i] << endl;         return;       }     cout <<  OK  << endl;   }   int main() { run(); }   