#include<bits/stdc++.h>
using namespace std;
const int N = (int)2e5+3;
const int MOD = (int)1e6+3;
int n, k, r, a[N], c[N], cnt[N];
int b[11];
int main() {
ios_base::sync_with_stdio(NULL);
cin.tie(0);
cin >> n >> k >> r;
for(int i = 1; i <= n; ++i) {
cin >> a[i];
}
for(int i = 1; i <= r; ++i) {
int x, y;
cin >> x >> y;
c[x]=y;
b[i]=x;
}
int j = 1;
int ans = n+1, kol = 0;
for(int i = 1; i <= n; ++i) {
cnt[a[i]]++;
if(cnt[a[i]] == c[a[i]] && c[a[i]] != 0) {
kol++;
}
while(j<=i && cnt[a[j]]-1>=c[a[j]]) {
cnt[a[j]]--;
j++;
}
if(kol == r) {
ans = min(ans, i-j+1);
}
}
if(ans == n+1) {
cout << "impossible";
return 0;
}
cout << ans;
return 0;
}
