#include <bits/stdc++.h>
using namespace std;
#define int long long
const int mxN = 105;
const int inf = 2e18 + 4;
int a[mxN], n, s, b, cur;
vector<vector<int>> dp;
int f(int i, int s){
if(s < 0) return inf;
if(i == n) return 0;
//if(dp[i][s] != -1) return dp[i][s];
int ans = inf;
for(int j = i + 1; j <= n; ++j){
ans = min(ans, f(j, s - 1));
if((a[j] - a[i] + 1) > cur) break;
}
for(int j = i + 1; j <= n; ++j){
ans = min(ans, f(j, s) + 1);
if((a[j] - a[i] + 1) > 2 * cur) break;
}
return dp[i][s] = ans;
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
cin >> n >> s >> b;
for(int i = 0; i < n; ++i){
cin >> a[i];
}
a[n] = inf;
sort(a, a + n);
int st = 0, en = inf, ans = 0;
while(st <= en){
int mid = st + (en - st) / 2;
cur = mid;
dp = vector<vector<int>>(n + 5, vector<int>(s + 5, -1));
if(f(0, s) <= b){
ans = mid;
en = mid - 1;
}else{
st = mid + 1;
}
}
cout << ans << "\n";
return 0;
}
