#include <bits/stdc++.h>
using namespace std;
#define NMAX 1000005
#define MOD 1000000007
#define ll long long
#define pb push_back
int v[NMAX], f[NMAX], n, a, b;
bool check(int x) {
int l = 1;
for (int r = 1; r <= n; r++) {
while (l <= n && (v[r] - v[l] >= x || r - l + 1 > b)) {
if (l + 1 == r && v[r] - v[l] > x && v[r + 1] != v[r])
return false;
l++;
if (l > r)
return false;
}
}
return true;
}
int main() {
int r = 0, minn = INT_MAX, maxx = INT_MIN;
cin >> n >> a >> b;
for (int i = 1; i <= n; i++) cin >> v[i];
sort(v + 1, v + 1 + n);
for (int i = 2; i <= n; i++) {
minn = min(minn, v[i] - v[i - 1]);
maxx = max(maxx, v[i] - v[i - 1]);
}
int st = minn, dr = maxx;
while (st <= dr) {
int mid = (st + dr) / 2;
if (check(mid)) {
r = mid;
dr = mid - 1;
} else st = mid + 1;
}
cout << r;
return 0;
}
/*
8 3 5
1 1 1 5 6 6 7 11
8 3 5
1 5 8 8 1 1 8 10
*/
