#include<bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define f first
#define s second
#define pb push_back
#define all(x) x.begin(),x.end()
#define vi vector<int>
#define vvi vector<vi>
#define vp vector<pii>
using namespace std;
const int N=2e5+5;
unordered_map<ll,int>mp,up;
ll a[N];
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);
int n,k,R;cin>>n>>k>>R;
for(int i=0;i<n;i++)cin>>a[i],mp[a[i]]=0;
ll l=1,r=n+1;
for(int i=0;i<R;i++){
ll b,q;cin>>b>>q;up[b]=q;
}
while(l<r){
int m=(l+r)>>1;
for(auto it : mp)mp[it.f]=0;
for(int i=0;i<m;i++)mp[a[i]]++;
int cnt=0;bool ch=0;
for(auto it : mp)if(up.find(it.f)!=up.end()&&it.s>=up[it.f])cnt++;
if(cnt==R)ch=1;
for(int i=m;i<n;i++){
if(up.find(a[i-m])!=up.end()&&mp[a[i-m]]==up[a[i-m]])cnt--;
mp[a[i-m]]--;
if(up.find(a[i])!=up.end()&&mp[a[i]]==up[a[i]]-1)cnt++;
mp[a[i]]++;
if(cnt==R)ch=1;
}if(ch)r=m;
else l=m+1;
}
if(l==n+1)cout<<"impossible";
else cout<<l;
}
