#include<bits/stdc++.h>
#define pint pair<int,int>
#define N 2005
#define pb push_back
#define ff first
#define ss second
#define mod 1000000007
#define INF 1000000005
#define pu push
using namespace std;
int n,a,b;
int arr[N],num;
int dp[N][N];
pint go[N];
inline int f(int ind,int x)
{
if(x<0)
return INF;
if(dp[ind][x]!=-1)
return dp[ind][x];
if(ind==n)
return 0;
if(go[ind].ff==0)
{
int goa=lower_bound(arr,arr+n,arr[ind]+num)-arr;
int gob=lower_bound(arr,arr+n,arr[ind]+2*num)-arr;
go[ind].ff=goa;
go[ind].ss=gob;
}
return dp[ind][x]=min(f(go[ind].ff,x-1),f(go[ind].ss,x)+1);
}
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
cin>>n>>a>>b;
for(int i=0;i<n;i++)
{
cin>>arr[i];
}
sort(arr,arr+n);
if((a+b)>=n)
{
cout<<"1\n";
return 0;
}
int l=0,r=1000000002/(a+b)+100;
int ans=r;
while(l<=r)
{
memset(dp,-1,sizeof(dp));
memset(go,0,sizeof(go));
int mid=(l+r)/2;
num=mid;
if(f(0,a)<=b)
{
ans=min(ans,mid);
r=mid-1;
}
else
{
l=mid+1;
}
}
cout<<ans<<endl;
return 0;
}
