#include <bits/stdc++.h>
#include <bits/extc++.h>
using namespace __gnu_pbds;
using namespace std;
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define ff first
#define sc second
#define pb push_back
#define ll long long
#define pll pair<ll, ll>
#define pii pair<int, int>
#define ull unsigned long long
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rngl(chrono::steady_clock::now().time_since_epoch().count());
// #define int long long
// #define int unsigned long long
// #define ordered_set(T) tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>
// #define ordered_multiset(T) tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>
// const ll mod = 1e9 + 7;
// const ll mod = 998244353;
const ll inf = 1e9;
const ll biginf = 1e18;
const int maxN = 1e5 + 15;
void solve() {
int n, k, r;
cin >> n >> k >> r;
int arr[n + 1], cnt[k + 1]{};
for (int i = 1; i <= n; i++)
cin >> arr[i];
for (int i = 1; i <= r; i++) {
int b, q; cin >> b >> q; cnt[b] = q;
}
int need = r, pos = -1;
for (int i = 1; i <= n; i++) {
cnt[arr[i]]--; if (cnt[arr[i]] == 0) need--;
if (need == 0) { pos = i; break; }
}
if (pos == -1) {
cout << "impossible"; return;
}
int ans = pos;
for (int i = 2; i <= n; i++) {
cnt[arr[i - 1]]++;
while (cnt[arr[i - 1]] > 0 && pos + 1 <= n) {
pos++; cnt[arr[pos]]--;
}
if (cnt[arr[i - 1]] > 0) break;
ans = min(ans, pos - i + 1);
}
cout << ans;
}
int32_t main() {
// #ifndef ONLINE_JUDGE
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
// #endif
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
int t = 1;
// cin >> t;
while (t--) {
solve();
// cout << '\n';
}
return 0;
}
