/**
____ ____ ____ ____ ____
||a |||t |||o |||d |||o ||
||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|
**/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N_MAX = 200000;
int N, K, R;
int D[N_MAX + 2];
int Q[N_MAX + 2];
int cnt[N_MAX + 2];
int ok;
int main () {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> N >> K >> R;
for (int i = 1; i <= N; i++) {
cin >> D[i];
}
for (int i = 1; i <= R; i++) {
int B;
cin >> B;
cin >> Q[B];
}
ok = K - R;
int r = 0;
while (r <= N && ok < K) {
r++;
if (cnt[D[r]] + 1 == Q[D[r]]) {
ok++;
}
cnt[D[r]]++;
}
if (r == N + 1) {
cout << "impossible\n";
return 0;
}
int answer = INT_MAX;
int l = 1;
while (r <= N) {
while (l < r && cnt[D[l]] - 1 >= Q[D[l]]) {
cnt[D[l]]--;
l++;
}
answer = min(answer, r - l + 1);
cnt[D[++r]]++;
}
cout << answer << "\n";
return 0;
}
