#include<bits/stdc++.h> using namespace std; #define int long long signed main(){ ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); int n, k, r; cin >> n >> k >> r; vector<int> a(n + 1), req(n + 1); for(int i = 1; i <= n; i++) cin >> a[i]; set<int> s; for(int i = 1; i <= r; i++){ int b, q; cin >> b >> q; req[b] = q; s.insert(b); } vector<int> cnt(n + 1); int ans = 1e9; for(int i = 1, j = 1; i <= n; i++){ while(j <= n && s.size()){ cnt[a[j]]++; if(cnt[a[j]] >= req[a[j]]) s.erase(a[j]); j++; } if(s.empty()) ans = min(ans, j - i); cnt[a[i]]--; if(cnt[a[i]] < req[a[i]]) s.insert(a[i]); j = max(j, i + 1); } if(ans == 1e9) cout << "impossible"; else cout << ans; }