#include <bits/stdc++.h>
using namespace std;
#define int long long
int32_t main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n, k, ri;
cin >> n >> k >> ri;
int dna[n];
for(int i = 0; i < n; i++) cin >> dna[i];
int req[k];
for(int i = 0; i < k; i++) req[i] = LLONG_MAX / 20;
for(int i = 0; i < ri; i++) {
int a, b;
cin >> a >> b;
req[a] = b;
}
int cnt[k];
memset(cnt, 0, sizeof(cnt));
unordered_set<int> s;
int ans = LLONG_MAX / 20, l = 0;
for(int r = 0; r < n; r++) {
cnt[dna[r]]++;
if(cnt[dna[r]] >= req[dna[r]]) s.emplace(dna[r]);
else continue;
if(s.size() == ri){
while(1){
ans = min(r - l + 1, ans);
cnt[dna[l]]--;
if(cnt[dna[l]] < req[dna[l]]) {
s.erase(dna[l]);
break;
}
l++;
}
}
}
if(ans == LLONG_MAX / 20) cout << "impossible";
else cout << ans;
}
