#include <bits/stdc++.h>
using namespace std;
long long n, p, q, a[2005], mini, medi, maxi, far, dp[2005][2005];
long long need(long long idx, long long big, long long w){
if(idx < 0) return 0;
if(dp[idx][big] != -1) return dp[idx][big];
dp[idx][big] = INT_MAX;
if(big > 0){
far = upper_bound(a, a+n, a[idx]-w-w)-a;
far--;
dp[idx][big] = min(dp[idx][big], need(far, big-1, w));
}
far = upper_bound(a, a+n, a[idx]-w)-a;
far--;
dp[idx][big] = min(dp[idx][big], (long long) (need(far, big, w)+1));
return dp[idx][big];
}
int main(){
cin >> n >> p >> q;
if(p+q >= n){
cout << 1;
return 0;
}
for(int i = 0; i < n; i++) cin >> a[i];
sort(a, a+n);
mini = 0; maxi = a[n-1]+1;
while(mini < maxi){
medi = mini+(maxi-mini)/2;
memset(dp, -1, sizeof(dp));
if(need(n-1, q, medi) <= p) maxi = medi;
else mini = medi+1;
}
cout << mini;
}
