#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 1000000;
int times[MAX_N+5];
int N, A, B;
bool isFeasible(int maxDiff) {
int groupCount = 0; // Count of groups formed
int groupStart = 0; // Index of the start of the current group
for (int i = 0; i < N; ++i) {
// If the current swimmer can't be added due to exceeding maxDiff
if (times[i] - times[groupStart] > maxDiff || i - groupStart + 1 > B) {
// Check if the previous group size is valid
if (i - groupStart < A) return false;
// Start a new group
groupStart = i;
++groupCount;
}
}
// Check the size of the last group
if (N - groupStart < A) return false;
return true;
}
int main() {
cin >> N >> A >> B;
for (int i = 0; i < N; ++i) {
cin >> times[i];
}
//Sort
sort(times, times + N);
//Binary search for the minimum maximum difference
int low = 0;
int high = times[N - 1] - times[0];
int result = high;
while (low <= high) {
int mid = low + (high - low) / 2;
// Check if this mid value is feasible
if (isFeasible(mid)) {
result = mid; // Update result and try for a smaller maximum difference
high = mid - 1;
} else {
low = mid + 1;
}
}
cout << result << "\n";
return 0;
}
