/*
no more temmy :(
*/
#include<bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
// #include<icecream.hpp>
// using namespace icecream;
#define ll long long
#define int ll
#define ld long double
#define y1 cheza
// mt19937 rng(1983413);
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template<class T> using ordered_set = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
const int N=2e5+100;
const int M=1e3+1;
const int B=317;
const int mod=1e9+7;
const int INF=1e18;
const int lg=64;
const int dx[]={1,-1,0,0};
const int dy[]={0,0,1,-1};
const double eps=1e-9;
int n,k,rr;
int a[N];
int b[N],q[N];
bool bad(){
map<int,int>cnt;
for(int i=1;i<=n;i++){
cnt[a[i]]++;
}
for(int i=1;i<=rr;i++){
if(cnt[b[i]]<q[i]){
return 1;
}
}
return 0;
}
void mem(){
map<int,int>m;
for(int i=1;i<=n;i++){
m[a[i]]=0;
}
for(int i=1;i<=rr;i++){
m[b[i]]=i;
}
for(int i=1;i<=n;i++){
a[i]=m[a[i]];
}
for(int i=1;i<=rr;i++){
b[i]=m[b[i]];
}
}
int pref[N][11];
bool check(int l,int r){
for(int i=1;i<=rr;i++){
int cnt=pref[r][b[i]]-pref[l-1][b[i]];
if(cnt<q[i])return 0;
}
return 1;
}
void test(){
cin>>n>>k>>rr;
for(int i=1;i<=n;i++){
cin>>a[i];
}
for(int i=1;i<=rr;i++){
cin>>b[i]>>q[i];
}
if(bad()){
cout<<"impossible\n";
return;
}
int ans=INF;
mem();
for(int i=1;i<=n;i++){
for(int j=1;j<=rr;j++){
pref[i][j]=pref[i-1][j];
}
pref[i][a[i]]++;
}
for(int i=1;i<=n;i++){
int l=i;
int r=n;
if(check(i,n)==0)break;
while(l<=r){
int mid=(l+r)>>1ll;
if(check(i,mid)){
r=mid-1;
}
else{
l=mid+1;
}
}
r++;
ans=min(ans,r-i+1);
}
cout<<ans<<'\n';
}
/*
*/
signed main(){
// ic.prefix("debug->| ");
// freopen("input.txt","r",stdin);
// freopen("output.txt","w",stdout);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
// cout.tie(nullptr);
long long t2=1;
// cin>>t2;
for(int i=1;i<=t2;i++){
test();
}
return 0;
}
