#include <bits/stdc++.h>
using namespace std;
const int N = 2e3 + 10;
int n, p, q, a[N], f[N][N];
int tk(int d, int c, int k){
int ans=-1;
while (d<=c){
int g=(d+c)/2;
if (a[g]>=k){
ans=g;
c=g-1;
} else d=g+1;
}
return ans;
}
int check(int i, int cn, int cl, int w){
if (cn < 0 || cl < 0) return 0;
if (i==-1) return 1;
int &res = f[cn][cl];
if (res!=-1) return res;
res = 0;
if (check(tk(1, n, a[i]+w), cn-1, cl, w)==1) return res=1;
if (check(tk(1, n, a[i]+2*w), cn, cl-1, w)==1) return res=1;
return res;
}
int solve(int d, int c){
int ans=-1;
while (d<=c){
int g=(d+c)/2;
memset(f, -1, sizeof(f));
if (check(1, p, q, g)){
ans=g;
c=g-1;
} else d=g+1;
}
return ans;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n >> p >> q;
q=min(q, n);
p=min(p, n);
for (int i=1; i<=n; ++i) cin >> a[i];
sort (a+1, a+n+1);
cout << solve(0, 1e9);
}
