/*
~2021~
*/
# include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
#define fi first
#define se second
typedef long long ll;
#define pii pair<int,int>
#define debug(x) cout << #x << '=' << x << endl;
const int N = 2e5 + 5;
const int INF = 1e9;
const ll mod = 1e9+7;
int need[N],arr[N],n,k,q,byk[N];
bool valid(int x){
for(int i = 0;i<k;i++) byk[i] = 0;
int cnt = 0;
for(int i = 1;i<=n;i++){
if(i > x){
if(byk[arr[i-x]] == need[arr[i-x]]) cnt--;
byk[arr[i-x]]--;
}
byk[arr[i]]++;
if(byk[arr[i]] == need[arr[i]]) cnt++;
if(cnt == q) return true;
}
return false;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
//freopen(,r,stdin);
//freopen(,w,stdout);
cin>>n>>k>>q;
for(int i = 1;i<=n;i++) cin>>arr[i];
for(int i = 1;i<=q;i++){
int x,y;
cin>>x>>y;
need[x] = y;
}
int ki = 1,ka = n;
int pos = -1;
while(ki <= ka){
int mid = (ki + ka)/2;
if(valid(mid)){
pos = mid;
ka = mid-1;
}
else{
ki = mid + 1;
}
}
if(pos == -1) cout<<"impossible"<<endl;
else cout<<pos<<endl;
}
