/*
_,add8ba,
,d888888888b,
d8888888888888b _,ad8ba,_
d888888888888888) ,d888888888b,
I8888888888888888 _________ ,8888888888888b
__________`Y88888888888888P"""""""""""baaa,__ ,888888888888888,
,adP"""""""""""9888888888P""^ ^""Y8888888888888888I
,a8"^ ,d888P"888P^ ^"Y8888888888P'
,a8^ ,d8888' ^Y8888888P'
a88' ,d8888P' I88P"^
,d88' d88888P' "b,
,d88' d888888' `b,
,d88' d888888I `b,
d88I ,8888888' ___ `b,
,888' d8888888 ,d88888b, ____ `b,
d888 ,8888888I d88888888b, ,d8888b, `b
,8888 I8888888I d8888888888I ,88888888b 8,
I8888 88888888b d88888888888' 8888888888b 8I
d8886 888888888 Y888888888P' Y8888888888, ,8b
88888b I88888888b `Y8888888^ `Y888888888I d88,
Y88888b `888888888b, `""""^ `Y8888888P' d888I
`888888b 88888888888b, `Y8888P^ d88888
Y888888b ,8888888888888ba,_ _______ `""^ ,d888888
I8888888b, ,888888888888888888ba,_ d88888888b ,ad8888888I
`888888888b, I8888888888888888888888b, ^"Y888Y"^ ____.,ad88888888888I
88888888888b,`888888888888888888888888b, "" ad888888888888888888888'
8888888888888698888888888888888888888888b_,ad88ba,_,d88888888888888888888888
88888888888888888888888888888888888888888b,`""""" d8888888888888888888888888I
8888888888888888888888888888888888888888888baaad888888888888888888888888888'
Y8888888888888888888888888888888888888888888888888888888888888888888888888P
I888888888888888888888888888888888888888888888P^ ^Y8888888888888888888888'
`Y88888888888888888P88888888888888888888888888' ^88888888888888888888I
`Y8888888888888888 `8888888888888888888888888 8888888888888888888P'
`Y888888888888888 `888888888888888888888888, ,888888888888888888P'
`Y88888888888888b `88888888888888888888888I I888888888888888888'
"Y8888888888888b `8888888888888888888888I I88888888888888888'
"Y88888888888P `888888888888888888888b d8888888888888888'
^""""""""^ `Y88888888888888888888, 888888888888888P'
"8888888888888888888b, Y888888888888P^
`Y888888888888888888b `Y8888888P"^
"Y8888888888888888P `""""^
`"YY88888888888P'
^""""""""'
*Allah is watching me :) *
*/
#include<bits/stdc++.h>
#define ll long long
#define yes "YES\n"
#define no "NO\n"
#define all(v) v.begin(), v.end()
#define pb push_back
#define F first
#define S second
#define mk make_pair
#define skip continue;
#define ld long double
using namespace std;
const int e=1e9+11;
const int L=1e7+11;
const int N=2e5+11;
const ll inf=1e18;
const int mod=1e9+7;
void solve(){
int n,k,d;
cin>>n>>k>>d;
int a[n+1];
for(int i=1; i<=n; i++){
cin>>a[i];
}
map<int,int>mp,had;
int ans=INT_MAX;
for(int i=1; i<=d; i++){
int u,v;
cin>>u>>v;
had[u]=1;
mp[u]=v;
}
int l=1,r=1,c=d;
while(r<=n){
int v=a[r];
mp[v]--;
if(mp[v]==0){
c--;
if(c==0){
while((mp[a[l]]+1<=0 || !had[a[l]]) && l<=r){
if(had[a[l]]){
mp[a[l]]++;
}
l++;
}
ans=min(ans,r-l+1);
mp[a[l]]++;
if(mp[a[l]]>0){
c++;
}
l++;
}
}
r++;
}
if(ans==INT_MAX){
cout<<"impossible"<<endl;
return;
}
cout<<ans<<endl;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
//freopen("sum2.in", "r", stdin);
//freopen("sum2.out", "w", stdout);
int tt=1,time=1;
// cin>>tt;
while(tt--){
solve();
}
}
