#include <bits/stdc++.h>
using namespace std;
#define int long long
const int mxN = 2005;
const int inf = 2e18 + 4;
int a[mxN], n, s, b, cur;
int find(int i, int x){
int st = i + 1, en = n - 1, ans = n;
while(st <= en){
int mid = st + (en - st) / 2;
if((a[mid] - a[i] + 1) > x){
en = mid - 1;
ans = mid;
}else{
st = mid + 1;
}
}
return ans;
}
/*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];
return dp[i][s] = min(f(find(i, 2 * cur), s) + 1, f(find(i, cur), s - 1));
}*/
int f(int x){
vector<vector<int>> dp(n + 5, vector<int>(s + 5, inf));
for(int j = 0; j <= s; ++j) dp[n][j] = 0;
for(int i = n - 1; i >= 0; --i){
int u = find(i, x), v = find(i, 2 * x);
for(int j = 0; j <= s; ++j){
dp[i][j] = min((j ? dp[u][j - 1] : inf), dp[v][j] + 1);
}
}
return dp[0][s];
}
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];
}
sort(a, a + n);
int st = 1, en = 1e9 + 1, ans = 0;
while(st <= en){
int mid = st + (en - st) / 2;
if(f(mid) <= b) ans = mid, en = mid - 1;
else st = mid + 1;
}
cout << ans << "\n";
return 0;
}
