// Success consists of going from failure to failure without loss of enthusiasm
#include <bits/stdc++.h>
using namespace std;
#define nl '\n'
int main() {
cin.tie(0)->sync_with_stdio(0);
int N, K, R; cin >> N >> K >> R;
vector<int> A(N); for(auto& x : A) cin >> x;
vector<vector<int>> oc(K); for(int i = 0; i < N; i++) oc[A[i]].push_back(i);
vector<int> Q(K, -1);
for(int i = 0; i < R; i++) {
int x, y; cin >> x >> y; Q[x] = --y;
}
set<int> S;
for(int i = 0; i < K; i++) {
if (Q[i] == -1) continue;
if (Q[i] >= int(size(oc[i]))) {
cout << "impossible" << nl;
return 0;
}
S.insert(oc[i][Q[i]]);
}
int ans = N + 1;
for(int l = 0; l < N; l++) {
int x = A[l];
int r = *rbegin(S);
ans = min(ans, r - l + 1);
S.erase(oc[x][Q[x]]);
++Q[x];
if (Q[x] >= int(size(oc[x]))) break;
S.insert(oc[x][Q[x]]);
}
cout << ans << nl;
return 0;
}
/*
13 4 3
1 1 3 2 0 1 2 0 0 0 0 3 1
0 2
2 1
1 2
5 3 1
1 2 0 1 2
0 2
*/
