dna.cpp

#include <bits/stdc++.h>
using namespace std;

int main() {
  int n, k, r;
  cin >> n >> k >> r;
  vector<int> a(n);
  for (auto &i : a) {
    cin >> i;
  }
  vector<int> mem(k);
  for (int i = 0; i < r; i++) {
    int b, q;
    cin >> b >> q;
    mem[b] = q;
  }
  int i = 0, d = 0;
  vector<int> cnt(k);
  while (i < n) {
    cnt[a[i]]++;
    if (mem[a[i]] && cnt[a[i]] == mem[a[i]]) d++;
    if (d == r) break;
    i++;
  }
  if (i == n) {
    cout << "impossible" << '\n';
    return 0;
  }
  int ans = i + 1, j = 0;
  while (i < n) {
    while (!(mem[a[j]] && cnt[a[j]] == mem[a[j]])) {
      cnt[a[j]]--;
      j++;
    }
    ans = min(ans, i - j + 1);
    i++;
    cnt[a[i]]++;
  }
  cout << ans << '\n';
}