#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define mp make_pair
#define mt make_tuple
using namespace std;
void solve(){
int n,k,r; cin >> n >> k >> r;
int count[k]; memset( count, 0, sizeof count );
bool needs[k]; memset( needs, false, sizeof needs );
int a[n]; for( int i = 0; i < n; i++ ){ cin >> a[i]; count[ a[i] ]++; }
map<int,int> required;
set<int> unsatisfied;
for( int i = 0; i < r; i++ ){
int b,k; cin >> b >> k;
required[b] = k;
needs[b] = true;
unsatisfied.insert(b);
}
for( auto i : required ){
if( count[ i.first ] < i.second ){ cout << "impossible" << endl; return; }
}
// reset count
memset( count, 0, sizeof count );
// fill
int ind = 0;
while( !unsatisfied.empty() ){
count[ a[ind] ]++; // add him to list
if( needs[ a[ind] ] ){
if( unsatisfied.find( a[ind] ) != unsatisfied.end() && count[ a[ind] ] >= required[ a[ind] ] ){ unsatisfied.erase( a[ind] ); }
}
ind++;
}
//cout << ind << endl;
int ans = ind;
bool flag = false;
for( int rS = 0; rS < n-1; rS++ ){
count[ a[rS] ]--;
if( needs[ a[rS] ] ){
if( count[ a[rS] ] < required[ a[rS] ] ){ unsatisfied.insert( a[rS] ); }
}
while( !unsatisfied.empty() ){
if( ind == n ){ flag = true; break; }
count[ a[ind] ]++; // add him to list
if( needs[ a[ind] ] ){
if( unsatisfied.find( a[ind] ) != unsatisfied.end() && count[ a[ind] ] >= required[ a[ind] ] ){ unsatisfied.erase( a[ind] ); }
}
ind++;
}
if( flag ){ break; }
ans = min( ans, ind-rS-1 );
}
cout << ans << endl;
return;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int t = 1;
//cin >> t;
while (t--) { solve(); }
return 0;
}
