#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define pb push_back
#define ll long long
#define int long long
const long long inf=1e18;
const int MOD=998244353;
const int N=3e5+5;
int req[4];
signed main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int n,k,r; cin>>n>>k>>r;
int a[n],l=0;
for(int i=0;i<n;i++){
cin>>a[i];
}
for(int i=0;i<r;i++){
int x,y; cin>>x>>y;
req[x]=y;
}
int cnt0=0,cnt1=0,cnt2=0,cnt3=0,ans=inf;
for(int i=0;i<n;i++){
if(a[i]==0)cnt0++;
if(a[i]==1)cnt1++;
if(a[i]==2)cnt2++;
if(a[i]==3)cnt3++;
while(l<i){
if(req[0]>cnt0 || req[1]>cnt1 || req[2]>cnt2 || req[3]>cnt3)break;
if(a[l]==0)cnt0--;
if(a[l]==1)cnt1--;
if(a[l]==2)cnt2--;
if(a[l]==3)cnt3--;
l++;
if(req[0]>cnt0 || req[1]>cnt1 || req[2]>cnt2 || req[3]>cnt3){
l--;
if(a[l]==0)cnt0++;
if(a[l]==1)cnt1++;
if(a[l]==2)cnt2++;
if(a[l]==3)cnt3++;
break;
}
}
if(req[0]<=cnt0 && req[1]<=cnt1 && req[2]<=cnt2 && req[3]<=cnt3){
ans=min(ans,i-l+1);
}
}
if(ans==inf)cout<<"impossible";
else cout<<ans;
}
