#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); ll awa[r];
for(ll i=0;i<r;i++) {
ll a,b;cin>>a>>b;
req[a]=b;
awa[i]=a;
}
long long mean = LLONG_MAX;
for(ll i=0;i<n;i++){
q.push(c[i]);
cnt[c[i]]++;
bool flag=false;
for(auto j:awa){
if(cnt[j]<req[j])flag=true;
}
if(!flag){
while(cnt[q.front()]-1>=req[q.front()]){
cnt[q.front()]--;
q.pop();
}
}
if(!flag && q.size()<mean){
mean=q.size();
}
}
if (mean==inf){
cout<<"impossible";
return 0;
}
cout<<mean;
}
