#include<bits/stdc++.h>
using namespace std;
int a[2005], dp[2005][2005];
bool check(int w, int n, int x, int y)
{
memset(dp, 0x3f, sizeof(dp));
dp[0][0] = 0;
int j1 = 1, j2 = 1;
for(int i = 1; i <= n; i++){
while(a[j1] <= a[i] - w) j1++;
while(a[j2] <= a[i] - 2*w) j2++;
for(int j = 0; j <= n; j++){
if(j > 0) dp[i][j] = min(dp[i][j], dp[j1-1][j-1]);
dp[i][j] = min(dp[i][j], dp[j2-1][j] + 1);
}
}
for(int i = 0; i <= x; i++) if(dp[n][i] <= y) return 1;
return 0;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
int n, x, y; cin>>n>>x>>y;
for(int i = 1; i <= n; i++) cin>>a[i];
sort(a+1, a+n+1);
int l = 1, r = 1e9, ans = -1;
while(l <= r){
int mid = (l+r)/2;
if(check(mid, n, x, y) == 1){ans = mid; r = mid-1;}
else l = mid+1;
}
cout<<ans;
}
