#include "bits/stdc++.h"
using namespace std;
#define SZ(s) (int)s.size()
int n, k, r;
int main(){
ios::sync_with_stdio(false); cin.tie(nullptr);
cin >> n >> k >> r;
vector <int> a(n+1), vis(k+1,0), vis1(k+1,0);
for(int i = 1; i <= n; i++){
cin >> a[i];
}
for(int i = 1; i <= r; i++){
int b, q1;
cin >> b >> q1;
vis1[b] = 1;
vis[b] = q1;
}
int r1 = r, ind = 0, ans = n+1;
queue <int> q[k+1];
set <int> s;
for(int i = 1; i <= n; i++){
if(!vis1[a[i]]) continue;
if(!vis[a[i]]){
s.erase(s.find(q[a[i]].front()));
q[a[i]].pop();
q[a[i]].push(i);
s.insert(q[a[i]].front());
if(r1 == 0) ans = min(ans, i-(*s.begin())+1);
continue;
}
vis[a[i]]--;
if(vis[a[i]] == 0) r1--;
if(SZ(q[a[i]]) == 0) s.insert(i);
q[a[i]].push(i);
if(r1 == 0) ans = min(ans, i-(*s.begin())+1);
}
if(ans == n+1) cout << "impossible";
else cout << ans;
}
