//Bismillahir-Rahmanir-Rahim
#include <bits/stdc++.h>
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("O1,O2,O3,Ofast,unroll-loops")
#pragma GCC target("sse,sse2,sse3,sse4,sse4.1,sse4.2,popcnt,avx,avx2")
#define pb push_back
#define pii pair <int, int>
#define pll pair <long long, long long>
#define pld pair <long double, long double>
#define ll long long
#define ld long double
#define x first
#define y second
#define all(v) v.begin(),v.end()
#define sz(s) (int)s.size()
#define skip continue
#define bpop(x) (ll)__builtin_popcountll(x)
using namespace std;
const int N = 2e5 + 7;
const int M = 5e3 + 7;
const int maxA = 2e6 + 7;
const int inf = 1e9 + 7;
const ll INF = 2e18 + 7;
const int MOD = 1e9 + 7;
const ld eps = 1e-9;
pii dir[] = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//#define int long long
int n, k, q, a[N], req[N], t[4 * N];
void update(int v, int tl, int tr, int pos, int x) {
if (tl == tr) {
t[v] += x;
return;
}
int mid = (tl + tr) / 2;
if (pos <= mid)update(v * 2, tl, mid, pos, x);
else update(v * 2 + 1, mid + 1, tr, pos, x);
t[v] = max(t[v * 2], t[v * 2 + 1]);
}
void solve() {
cin >> n >> k >> q;
for (int i = 1;i <= n;i++)cin >> a[i], a[i]++;
for (int i = 1;i <= q;i++) {
int x, cnt;
cin >> x >> cnt;
req[++x] = cnt, update(1, 1, n, x, cnt);
}
int r = 0, ans = inf;
for (int l = 1;l <= n;l++) {
while (r < n && t[1] > 0)r++, update(1, 1, n, a[r], -1);
if (t[1] <= 0)ans = min(ans, r - l + 1);
update(1, 1, n, a[l], 1);
}
if (ans == inf)cout << "impossible";
else cout << ans;
}
signed main() {
//srand(time(NULL));
ios_base::sync_with_stdio(0);
cout.tie(0);
//freopen("tests.in", "r", stdin);
//freopen("milkorder.out", "w", stdout);
int test = 1;
//cin >> test;
for (int t = 1;t <= test;t++) {
//cout << "Case " << t << ": ";
solve();
}
return 0;
}
