#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
int n, k, R;
int niz[200005];
int treba[200005];
int br[200005];
bool check(int x){
for(int i=1; i<=k; i++){
br[i] = 0;
}
int cnt = 0;
for(int i=1; i<=x; i++){
br[niz[i]]++;
if(br[niz[i]] == treba[niz[i]]) cnt++;
}
if(cnt >= R) return 1;
for(int i=x+1; i<=n; i++){
br[niz[i]]++;
if(br[niz[i]] == treba[niz[i]]) cnt++;
br[niz[i-x]]--;
if(br[niz[i-x]] == treba[niz[i-x]]-1) cnt--;
if(cnt >= R) return 1;
}
return 0;
}
int main(){
ios_base::sync_with_stdio(false);
cout.precision(10);
cout<<fixed;
cin >> n >> k >> R;
for(int i=1; i<=n; i++){
cin >> niz[i];
niz[i]++;
}
for(int i=1; i<=k; i++){
treba[i] = n+500;
}
for(int i=1; i<=R; i++){
int a, b;
cin >> a >> b;
treba[a+1] = b;
}
int l = 1, r = n, res = n+1;
while(l <= r){
int mid = (l+r)/2;
if(check(mid)){
r = mid-1;
res = mid;
}
else l = mid+1;
}
if(res == n+1){
cout << "impossible\n";
}
else cout << res << "\n";
return 0;
}
