#include <bits/stdc++.h>
using namespace std;
int n, a[100010], k;

int main()
{
    cin>>n;
    for(int i = 0 ; i < n ; i++ ) cin>>a[i];
    cin>>k;
    int lb = 0, ub = 1000000000, md;
    while( lb < ub )
    {
        int ct = 0, cnt = 0;
        md = (lb+ub-1)/2;
        for(int i = 0 ; i < n ; i++ )
            if( a[i]-md > 0 ) ct += ((a[i]-md)/k) + (bool)((a[i]-md)%k);
        if( ct <= md ) ub = md;
        else lb = md+1;
    }
    cout<<ub<<endl;
}