#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;
#define calcdp for (int i = n - 1; i >= 0; i--) { int useq = lower_bound(a, a + n, a[i] + (2 * w)) - a; int usep = lower_bound(a, a + n, a[i] + w) - a; dp[i][0] = dp[useq][0] + 1; for (int j = 1; j <= p; j++) { dp[i][j] = min(dp[useq][j] + 1, dp[usep][j - 1]); } }
int n, p, q, a[2005];
int solve() {
int dp[n + 1][p + 1];
for (int i = 0; i <= p; i++) {
dp[n][i] = 0;
}
int minw = 1, maxw = 1e9;
while (maxw - minw >= 2) {
int w = (maxw + minw) / 2;
/*
for (int i = n - 1; i >= 0; i--) {
int useq = lower_bound(a, a + n, a[i] + (2 * w)) - a;
int usep = lower_bound(a, a + n, a[i] + w) - a;
dp[i][0] = dp[useq][0] + 1;
for (int j = 1; j <= p; j++) {
dp[i][j] = min(dp[useq][j] + 1, dp[usep][j - 1]);
}
}
*/
calcdp;
if (dp[0][p] <= q) maxw = w;
else minw = w + 1;
}
for (int w = minw; w <= maxw; w++) {
calcdp;
if (dp[0][p] <= q) return w;
}
return 1e9;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> p >> q;
for (int i = 0; i < n; i++) {
cin >> a[i];
}
sort(a, a + n);
cout << (p + q < n ? solve() : 1) << '\n';
return 0;
}
