#include <bits/stdc++.h>
using namespace std;
int const INF=1000000000;
int const MAX=200005;
int n,alsz,req;
int v[MAX];
int nec[MAX];
int lstap[MAX];
int urm[MAX];
int cnt[MAX];
int capat[MAX];
void read(){
cin>>n>>alsz>>req;
int i;
for(i=1;i<=n;++i)
cin>>v[i];
for(i=1;i<=req;++i){
int lit,nr;
cin>>lit>>nr;
nec[lit]=nr;
}
}
void precalc(){
int i;
for(i=n;i;--i){
urm[i]=lstap[v[i]];
lstap[v[i]]=i;
}
}
void minself(int& x,int val){
if(x>val)
x=val;
}
int solve(){
int i;
int ok=0;
for(i=1;i<=n && ok<req;++i){
++cnt[v[i]];
if(cnt[v[i]]==nec[v[i]])
++ok;
}
int ans;
if(ok<req)
ans=INF;
else{
set<int>beg;
int lt;
for(lt=0;lt<alsz;++lt)
if(nec[lt]){
capat[lt]=lstap[lt];
while(cnt[lt]>nec[lt]){
capat[lt]=urm[capat[lt]];
--cnt[lt];
}
beg.insert(capat[lt]);
}
ans=i-*beg.begin();
for(;i<=n;++i){
if(nec[v[i]]){
beg.erase(capat[v[i]]);
capat[v[i]]=urm[capat[v[i]]];
beg.insert(capat[v[i]]);
}
minself(ans,i-*beg.begin()+1);
}
}
return ans;
}
void write(int ans){
if(ans<INF)
cout<<ans;
else
cout<<"impossible";
}
int main()
{
read();
precalc();
write(solve());
return 0;
}
