#include <bits/stdc++.h>
using namespace std;
#define int long long
int32_t main(){
int n,k,r; cin>>n>>k>>r;
vector<int> dna(n);
for (int i = 0; i < n; i++)
{
cin>>dna[i];
}
vector<int> req(n, 0);
for (int i = 0; i < r; i++)
{
int b,q; cin>>b>>q;
req[b] = q;
}
vector<int> cnt(n, 0);
int L=0,R=0;
int valid = 0;
int ans = LLONG_MAX;
pair<int,int> ref;
while(R < n){
cnt[dna[R]]++;
if(cnt[dna[R]] == req[dna[R]] && req[dna[R]] != 0){
valid++;
}
if(valid == r){
ans = min(ans, R-L+1);
ref = {L, R};
}
while(valid == r){
cnt[dna[L]]--;
if(cnt[dna[L]] == req[dna[L]]-1 && req[dna[L]] != 0){
valid--;
}
L++;
if(valid == r){
ans = min(ans, R-L+1);
ref = {L, R};
}
}
R++;
}
if(ans == LLONG_MAX){
cout << "impossible";
return 0;
}
else{
cout << ans << endl;
}
}
