#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define pll pair<ll,ll>
#define qll queue<ll>
#define inf LLONG_MAX
#define test return 12;
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
ll n,k,r;cin>>n>>k>>r;
ll c[n]; qll q;
for(ll i=0;i<n;i++) {
c[i];cin>>c[i];
}
ll cnt[k],req[k]; fill(req,req+k,0); fill(cnt,cnt+k,0);
for(ll i=0;i<r;i++) {
ll a,b;cin>>a>>b;
req[a]=b;
}
ll lo=0,hi=n+1;
while(lo<hi-1){
ll x = (hi+lo)/2;
qll q;
ll satis=0;
bool flag=0;//satis??
fill(cnt,cnt+k,0);
for(ll i=0;i<x;i++) {
q.push(c[i]);
cnt[c[i]]++;
if(cnt[c[i]]==req[c[i]] and req[c[i]]!=0)satis++;
if(satis==r)flag=1;
}
for(ll i=x;i<n;i++) {
cnt[q.front()]--;
if(cnt[q.front()]==req[q.front()]-1)satis--;
q.pop();
q.push(c[i]);
cnt[c[i]]++;
if(cnt[c[i]]==req[c[i]])satis++;
if(satis==r)flag=1;
}
if(!flag){
lo=x;
} else{
hi=x;
}
}
if(hi==n+1){
cout<<"impossible";
return 0;
}
cout<<hi;
}
