//Dedicated to my love, ivaziva
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
using ll = int64_t;
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define pb push_back
#define dbg(x) cerr<<#x<<": "<<x<<'\n';
#define dbga(A,l_,r_){for(int i_=l_;i_<=r_;i_++)cerr<<A[i_]<<' ';cerr<<'\n';}
#define dbgv(a_){for(auto x_:a_) cerr<<x_<<' ';cerr<<'\n';}
const int maxn = 2e5 + 3;
int n, k, r;
int a[maxn], info[maxn], f[maxn];
void Add(int x, int& cnt) {
f[x]++;
if (f[x] == info[x]) {
cnt++;
}
}
void Erase(int x, int& cnt) {
if (f[x] == info[x]) {
cnt--;
}
f[x]--;
}
int32_t main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
cout.tie(nullptr); cerr.tie(nullptr);
cin >> n >> k >> r;
for (int i = 0; i < maxn; i++) {
info[i] = -1;
}
for (int i = 0; i < n; i++) {
cin >> a[i];
}
for (int i = 0; i < r; i++) {
int B, Q;
cin >> B >> Q;
info[B] = Q;
}
int cnt = 0;
int R = -1;
int ans = maxn;
for (int i = 0; i < n; i++) {
while (R + 1 < n && cnt < r) {
R += 1;
Add(a[R], cnt);
}
if (cnt == r) {
ans = min(ans, R - i + 1);
}
Erase(a[i], cnt);
}
if (ans > n) {
cout << "impossible\n";
return 0;
}
cout << ans << '\n';
return 0;
}
