#include<bits/stdc++.h>
#define int long long
using namespace std;
int jvli,n,k;
int a[100010];
int cha(int l,int r){
	if(l>r){
		return l;
	}else{
		int mid=(l+r+1)/2;
		int dian=k;
		for(int i=2;i<=n;i++){
			if(a[i]-a[i-1]>mid){
				dian-=(a[i]-a[i-1])/mid;
			}
		}
		cout<<dian<<' '<<l<<' '<<mid<<' '<<r<<endl;
		if(dian<0){
			return cha(mid+1,r);
		}else{
			return cha(l,mid-1);
		}
	}
}
signed main(){
	cin>>jvli>>n>>k;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	cout<<cha(0,jvli);
	return 0;
}

WA#2、#10，RE#1