#include <bits/stdc++.h>
#define f0(i, n) for(int i(0); i < (n); i++)
#define f1(i, n) for(int i(1); i <= n; i++)
using namespace std;
typedef long long ll;
const int N = 2002;
int n, f[N][N];
int a[N], huge, tiny;
int lon[N], nho[N];
bool check(int mid){
f1(i, n){
int vt = lower_bound(a + 1, a + n + 1, a[i] - mid + 1) - a;
int vt2 = lower_bound(a + 1, a + n + 1, a[i] - 2*mid + 1) - a;
lon[i] = vt2;
nho[i] = vt;
}
f0(i, tiny + 1) f[0][i] = 0;
f1(i, n){
f0(j, tiny + 1){
/// nho
int k = nho[i] - 1;
if(j > 0){
f[i][j] = min(f[i][j], f[k][j - 1]);
}
k = lon[i] - 1;
int g = f[k][j] + 1;
if(g > huge) g = 1e9;
f[i][j] = min(f[i][j], g);
}
}
f0(j, tiny + 1) if(f[n][j] <= huge) return 1;
return 0;
}
int main(){
ios_base::sync_with_stdio(0);
cin >> n >> tiny >> huge;
f1(i, n) cin >> a[i];
if(tiny + huge >= n){
cout << 1;
return 0;
}
sort(a + 1, a + n + 1);
int l = 0, r = 1e6 + 2, ans = r;
while(l <= r){
int mid = (l + r)/2;
f1(i, n) f0(j, tiny + 1) f[i][j] = 1e9;
if(check(mid)) r = mid - 1, ans = mid;
else l = mid + 1;
}
cout << ans;
}
