#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
const int N = 201;
const int INF = 1e9;
const ll LLINF = 9e18;
const ll MOD = 1e9 + 7;
#define all(x) (x).begin(), (x).end()
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// typedef __gnu_pbds::tree<int, __gnu_pbds::null_type, less<int>, __gnu_pbds::rb_tree_tag, __gnu_pbds::tree_order_statistics_node_update> ordered_set;
void solve()
{
int n, k, r;
cin >> n >> k >> r;
int a[n];
for(int i = 0; i < n; i++)
cin >> a[i];
int rq[k] = {};
int cnt[k] = {};
for(int i = 0; i < r; i++)
{
int u, v;
cin >> u >> v;
rq[u] = v;
}
int gd = 0;
int l1 = 0, r1 = 0, ans = INF;
while(gd != r && r1 != n)
{
cnt[a[r1]]++;
if(cnt[a[r1]] == rq[a[r1]])
gd++;
r1++;
}
if(gd != r)
{
cout << "impossible";
return;
}
ans = r1 - l1;
while(r1 != n)
{
while(gd != r && r1 != n)
{
cnt[a[r1]]++;
if(cnt[a[r1]] == rq[a[r1]])
gd++;
r1++;
}
if(cnt[a[l1]] == rq[a[l1]])
{
gd--;
}
cnt[a[l1]]--;
l1++;
ans = min(ans, r1 - l1 + 1);
}
cout << ans << '\n';
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
while (t--)
{
solve();
cout << '\n';
}
}
