#include<bits/stdc++.h>
using namespace std;
const int nx = 2e3+5;
int n,p,q,arr[nx],dp[nx][nx];
bool ok(int x)
{
memset(dp, 0x3f, sizeof dp);
dp[0][0] = 0;
for(int i = 1; i <= n; i++)
{
int l = upper_bound(arr+1,arr+1+i,arr[i]-x)-arr-1;
int r = upper_bound(arr+1,arr+1+i,arr[i]-2*x)-arr-1;
dp[i][0] = dp[r][0]+1;
for(int j = 1; j <= min(i,p); j++)
{
dp[i][j] = dp[i][j-1];
dp[i][j] = min({dp[i][j], dp[l][j-1], dp[r][j]+1});
}
}
return dp[n][min(n,p)] <= q;
}
int main()
{
ios::sync_with_stdio(false); cin.tie(0);
cin>>n>>p>>q;
for(int i = 1; i <= n; i++) cin>>arr[i];
sort(arr+1,arr+1+n);
int l = 1, r = 1e9+5;
while(l<r)
{
int mid = (l+r)/2;
if(ok(mid)) r = mid;
else l = mid+1;
}
cout<<l;
}
