#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define int long long
#define mod 1000000007
#define ld long double
#define all(x) (x).begin() , (x).end()
#define pb push_back
using namespace __gnu_pbds;
using namespace std;
template <typename T>
using ordered_set = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
signed main(){
cin.tie(0)->sync_with_stdio(0);
ll tt=1;
// cin >> tt;
while(tt--){
ll n,k,r,en=0;
cin >> n >> k >> r;
vector<ll> a(n),f(k,0);
vector<array<ll,2>> b(r);
map<ll,ll> m;
for(int i=0; i<n; i++) cin >> a[i],f[a[i]]++;
for(int i=0; i<r; i++) cin >> b[i][0] >> b[i][1],m[b[i][0]]=b[i][1];
ll h=r,ans=n+1;
for(int st=0; st<n; st++){
while(h>0 && en<n){
m[a[en]]--;
if(m[a[en]]==0) h--;
en++;
}
if(h==0) ans=min(ans,en-st);
m[a[st]]++;
if(m[a[st]]==1) h++;
}
if(ans==n+1) cout << "impossible";
else cout << ans;
}
return 0;
}
