#include<bits/stdc++.h>
using namespace std;
int n,l,r,c[1000010],a[1000010],ans,k,t,f=1;
int main(){
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>a[i];
    }
    cin>>k;
    l=1,r=1,c[a[1]]++,a[n+1]=a[n];
    while(r<=n&&l<=n){
        if(f==1){
            ans=max(ans,r-l+1);
            r++;
            c[a[r]]++;
            if(c[a[r]]>k){
                f=0;
                t=a[r];
            }
        }else{
            c[a[l]]--;
            l++;
            if(c[t]<=k){
                f=1;
            }
        }
    }
    cout<<ans;
    return 0;
}