#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
void debug_out() { cerr << endl; }
template<typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
cerr << "[" << H << "]";
debug_out(T...);
}
#ifdef dddxxz
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
#define SZ(s) ((int)s.size())
#define all(x) (x).begin(), (x).end()
#define revall(x) (x).rbegin(), (x).rend()
clock_t startTime;
double getCurrentTime() {
return (double) (clock() - startTime) / CLOCKS_PER_SEC;
}
#define MP make_pair
typedef long long ll;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
const double eps = 0.00001;
const int MOD = 1e9 + 7;
const int INF = 1000000101;
const long long LLINF = 1223372000000000555;
const int N = 2e5 + 3e2;
const int M = 222;
int a[N];
int diff = 0;
int cnt[N], need[N];
void add(int i){
int x = a[i];
if (need[x] == 0) return;
cnt[x]++;
if (cnt[x] == need[x]) diff++;
}
void del(int i){
int x = a[i];
if (need[x] == 0) return;
cnt[x]--;
if (cnt[x] == need[x] - 1) diff--;
}
int n, k, q;
bool check(int len){
fill(cnt, cnt + k, 0);
diff = 0;
for (int i = 1; i <= n; i++){
add(i);
if (i > len) del(i - len);
if (diff == q) return true;
}
return false;
}
void solve(int TC) {
cin >> n >> k >> q;
for (int i = 1; i <= n; i++) cin >> a[i];
for (int i = 1; i <= q; i++){
int x, y;
cin >> x >> y;
need[x] = y;
}
int ans = -1;
int l = 1, r = n;
while (l <= r){
int m = (l + r) >> 1;
if (check(m)){
ans = m;
r = m - 1;
} else l = m + 1;
}
if (ans == -1) cout << "impossible"; else
cout << ans;
}
int main() {
startTime = clock();
cin.tie(nullptr); cout.tie(nullptr);
ios_base::sync_with_stdio(false);
bool llololcal = false;
#ifdef dddxxz
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
llololcal = true;
#endif
int TC = 1;
//cin >> TC;
for (int test = 1; test <= TC; test++) {
//debug(test);
//cout << "Case #" << test << ": ";
solve(test);
}
if (llololcal) cerr << endl << "Time: " << int(getCurrentTime() * 1000) << " ms" << endl;
return 0;
}
