#include<iostream>
#include<vector>
#include<set>
#include<map>
#include<unordered_map>
#include<algorithm>
#include<bitset>
#include<queue>
#include<numeric>
#include<climits>
#include<cstring>
#include<cmath>
using namespace std;
#define int long long
int n,k,R;
void solve() {
cin>>n>>k>>R;
int a[n];
int cnt[k];
int mn[k];
memset(cnt, 0, sizeof(cnt));
memset(mn,0,sizeof(mn));
for(int i=0;i<n;i++) {
cin>>a[i];
}
for(int i=0;i<R;i++) {
int b,c;
cin>>b>>c;
mn[b]=c;
}
int l=0,r=0,z=0;
int mn1=n+1;
while(r<n) {
if(z!=R) {
cnt[a[r]]++;
if(cnt[a[r]]==mn[a[r]]) {
z++;
}
r++;
}
if(z==R) {
mn1=min(mn1,r-l);
}
if(z==R) {
if(cnt[a[l]]==mn[a[l]]) {
z--;
}
cnt[a[l]]--;
l++;
}
if(z==R) {
mn1=min(mn1,r-l);
}
}
if(mn1==n+1) {
cout<<"impossible\n";
return;
}
cout<<mn1<<'\n';
}
signed main() {
cin.tie(0)->sync_with_stdio(0);
cout.tie(0);
int t=1;
//cin>>t;
while(t--) {
solve();
}
}
