#include <bits/stdc++.h>
#include <climits>
// mrrrowwww meeowwwww :3
// go play vivid/stasis! !! !!! https://vividstasis.gay
#define fo(i, a, b) for (auto i = (a); i < (b); i++)
#define of(i, a, b) for (auto i = (b); i-- > (a);)
#define f first
#define s second
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define be(a) a.begin(), a.end()
using namespace std;
int ____init = []{
ios::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
return 0;
}();
int arr[200000];
int curr[200000];
int want[200000];
int can;
int main() {
int n, k, r; cin >> n >> k >> r; can = k;
fo(i, 0, n) cin >> arr[i];
fo(i, 0, r) {
int j, v; cin >> j >> v;
want[j] = v;
can--;
}
int res = INT_MAX;
for (int i = 0, j = 0; i < n; i++) {
curr[arr[i]]++;
if (curr[arr[i]] == want[arr[i]]) can++;
while (curr[arr[j]] > want[arr[j]]) curr[arr[j++]]--;
if (can >= k) res = min(res, i - j + 1);
}
if (res < INT_MAX) cout << res;
else cout << "impossible";
}
