#include <bits/stdc++.h>
#define int long long
#define forinc(a,b,c) for(int a=b,_c=c;a<=_c;++a)
#define reset(f, x) memset(f, x, sizeof(f))
using namespace std;
const int N=2010;
int n,p,q;
int a[N];
int f[N][N];
bool C(int x)
{
reset(f,-1);
f[0][p]=q;
forinc(i,0,n-1) forinc(j,0,p) if(f[i][j]>-1)
{
if(j)
{
int t=upper_bound(a+1,a+n+1,a[i+1]+x-1)-a-1;
f[t][j-1]=max(f[t][j-1],f[i][j]);
}
if(f[i][j])
{
int t=upper_bound(a+1,a+n+1,a[i+1]+x*2-1)-a-1;
f[t][j]=max(f[t][j],f[i][j]-1);
}
}
forinc(i,0,p) if(f[n][i]>-1) return 1;
return 0;
}
main()
{
//freopen("WATCHING.inp","r",stdin);
cin>>n>>p>>q;p=min(p,n),q=min(q,n);
for(int i=1; i<=n; ++i) cin>>a[i];
sort(a+1,a+n+1);
int l=1,m,r=1e9,ans;
while(l<=r)
{
m=l+(r-l)/2;
if(C(m)) ans=m,r=m-1;
else l=m+1;
}
cout<<ans;
}
