// اَللَهُمَ صَلِ عَلَىَ مُحَمَدٍ وَ آلِ مُحَمَدٍ
//#include "bits/stdc++.h"
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <queue>
#include <thread>
#include <fstream>
#include <stack>
using namespace std ;
#define int long long
#define pb push_back
#define si size()
#define fi first
#define se second
#define all(a) a.begin(),a.end()
#define applejuice ios::sync_with_stdio(false) ; cin.tie(nullptr) ; cout.tie(nullptr) ;
const int inf=1e18 ;
const int mod=1e9+7 ;
const int maxn=2*1e5+7 ;
int tt=1 ;
int a[maxn] , cnt[maxn] , cnt1[maxn] ;
void solve()
{
int n , r , k ;
cin >> n >> r >> k ;
for(int i=0 ; i<n ; i++) {cin >> a[i] ;}
int x , cntt , c=0 ;
for(int i=0 ; i<k ; i++) {cin >> x >> cntt ; cnt[x]=cntt ; c+=cnt[x] ;}
int s=c , e=n , mid , ans=-1 ;
while(s<=e)
{
mid=(s+e)/2 ;
bool A=0 ;
for(int i=0 ; i<mid ; i++) {cnt1[a[i]]+=1 ;}
int B=0 ;
for(int i=0 ; i<r ; i++) {B+=(cnt[i]<=cnt1[i] ? 1 : 0) ;}
A=(A|(B==r)) ;
//cout << 0 << " " << mid-1 << " " << (A ? 1 : 0) << "\n" ;
for(int i=0 ; mid+i<n ; i++)
{
if(cnt[a[i]]<=cnt1[a[i]] && cnt[a[i]]>cnt1[a[i]]-1) {B-=1 ;}
cnt1[a[i]]-=1 ;
if(cnt[a[mid+i]]>cnt1[a[mid+i]] && cnt[a[mid+i]]<=cnt1[a[mid+i]]+1) {B+=1 ;}
cnt1[a[mid+i]]+=1 ;
A=(A|(B==r)) ;
//cout << i << " " << mid+i << " " << (A ? 1 : 0) << "\n" ;
}
if(A) {ans=mid ; e=mid-1 ;}
else {s=mid+1 ;}
for(int i=0 ; i<r ; i++) {cnt1[i]=0 ;}
}
if(ans==-1) {cout << "impossible" ; return ;}
cout << ans ;
}
signed main()
{
//wrong
applejuice ;
//cin >> tt ;
while(tt--) {solve() ;}
}
/*
5 2 2
0 1 1 0 1
0 1
1 1
2
_______
13 4 3
1 1 3 2 0 1 2 0 0 0 0 3 1
0 2
2 1
1 2
7
_______
5 3 1
1 2 0 1 2
0 2
impossible
*/
