#include <bits/stdc++.h> using namespace std; int m,q,n,ans,l,r,u,v,ct[200005],now[200005],ok,a[200005]; int main(){ ios::sync_with_stdio(false); cin >> n >> m >> q; for (int i=1;i<=n;i++){ cin >> a[i]; } for (int i=1;i<=q;i++){ cin >> u >> v; ct[u]=v; } l=1; r=0; ans=1e9; while (l <= n && r <= n){ if (ok == q){ ans=min(ans,r-l+1); if (now[a[l]] == ct[a[l]]) ok--; now[a[l]]--; l++; } else { r++; now[a[r]]++; if (now[a[r]] == ct[a[r]]) ok++; } } if (ans == 1e9) cout << "impossible\n"; else cout << ans << "\n"; return 0; }