#include "testlib.h"

const int N = 1000005;

bool flag[N];

int main(int argc, char **argv) {
  registerTestlibCmd(argc, argv);
  int n = inf.readInt(), m = inf.readInt();
  for (int i = n - 1; i >= 0; --i) {
    int x = ouf.readInt(), y = ouf.readInt();
    if (x < 0 || x >= n || x != i) quitf(_wa, "x is invalid!");
    if (y < m || y >= m + n) quitf(_wa, "y is invalid");
    if ((x & y) != x) quitf(_wa, "x bitand y is not equal to x!");
    if (flag[y]) quitf(_wa, "Repeated elements!");
    flag[y] = true;
  }
  quitf(_ok, "OK!");
}