//
// main1.cpp
// problem1
//
// Created by Essa Almousa on 2030 / 01/ 01 AD.
//
#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
using ll = long long;
#define pb push_back
#define pF first
#define pS second
#define SP <<" "<<
const ll N = 3e5;
ll a[N], req[N], frq[N], ans1[N];
int main() {
ios::sync_with_stdio(0); cout.tie(0); cin.tie(0);
ll n, k, q;
cin>>n>>k>>q;
for (int i=0; i<n; i++) {
cin>>a[i];
ans1[a[i]] = 1;
}
for (int i=0; i<q; i++) {
ll x, y; cin>>x>>y;
req[x] = y;
ans1[x] = 0;
}
ll mn = INT_MAX, l = 0, r = -1;
ll ans = q;
while (r <= n-1 && l <= n-1) {
if (ans == 0) {
mn = min(mn, r-l+1);
}
if (ans != 0) {
r++;
if (r >= n) break;
frq[a[r]]++;
if (req[a[r]] <= frq[a[r]]) {
if (ans1[a[r]] == 0) {
ans1[a[r]] = 1;
ans--;
}
}
}
else if (ans == 0) {
frq[a[l]]--;
if (req[a[l]] > frq[a[l]]) {
if (ans1[a[l]] == 1) {
ans1[a[l]] = 0;
ans++;
}
}
l++;
}
}
if (ans == 0) {
mn = min(mn, r-l+1);
}
if (mn == INT_MAX) cout << "impossible";
else cout << mn;
}
