#include <stdio.h>
#define N 2000
int min(int a, int b) { return a < b ? a : b; }
unsigned int X = 12345;
int rand_() {
return (X *= 3) >> 1;
}
void sort(int *aa, int l, int r) {
while (l < r) {
int i = l, j = l, k = r, a = aa[l + rand_() % (r - l)], tmp;
while (j < k)
if (aa[j] == a)
j++;
else if (aa[j] < a) {
tmp = aa[i], aa[i] = aa[j], aa[j] = tmp;
i++, j++;
} else {
k--;
tmp = aa[j], aa[j] = aa[k], aa[k] = tmp;
}
sort(aa, l, i);
l = k;
}
}
int main() {
static int xx[N], dp[N + 1][N + 1];
int n, k_, l_, i, j1, j2, k, lower, upper;
scanf("%d%d%d", &n, &k_, &l_), k_ = min(k_, n), l_ = min(l_, n);
for (i = 0; i < n; i++)
scanf("%d", &xx[i]);
sort(xx, 0, n);
lower = 0, upper = 0x3f3f3f3f;
while (upper - lower > 1) {
int w = (lower + upper) / 2, ok;
for (i = 0; i <= n; i++)
for (k = 0; k <= k_; k++)
dp[i][k] = l_ + 1;
dp[0][0] = 0;
for (i = 0, j1 = 0, j2 = 0; i <= n; i++) {
while (j1 < n && xx[j1] - xx[i] < w)
j1++;
while (j2 < n && xx[j2] - xx[i] < w * 2)
j2++;
for (k = 0; k <= k_; k++) {
if (k < k_)
dp[j1][k + 1] = min(dp[j1][k + 1], dp[i][k]);
if (dp[i][k] < l_)
dp[j2][k] = min(dp[j2][k], dp[i][k] + 1);
}
}
ok = 0;
for (k = 0; k <= k_; k++)
if (dp[n][k] <= l_) {
ok = 1;
break;
}
if (ok)
upper = w;
else
lower = w;
}
printf("%d\n", upper);
return 0;
}
