#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int n, p, q, a[2010], l, r, w, ll, rr, mid, dp[2010][2010];
int main() {
cin >> n >> p >> q;
for (int i = 1; i <= n; i++) cin >> a[i];
sort(a+1,a+n+1);
l = 1; r = 1e9;
while (l <= r) {
w = (l+r)/2;
for (int i = 0; i <= n; i++) for (int j = 0; j <= min(n,q); j++) dp[i][j] = 1e9;
dp[0][0] = 0;
for (int i = 1; i <= n; i++) {
ll = 1; rr = i-1;
while (ll <= rr) {
mid = (ll+rr)/2;
if (a[mid] > a[i]-w) rr = mid-1;
else ll = mid+1;
}
for (int j = 0; j <= min(n,q); j++) if (dp[rr][j] < p) dp[i][j] = dp[rr][j]+1;
ll = 1; rr = i-1;
while (ll <= rr) {
mid = (ll+rr)/2;
if (a[mid] > a[i]-2*w) rr = mid-1;
else ll = mid+1;
}
for (int j = 1; j <= min(n,q); j++) dp[i][j] = min(dp[i][j],dp[rr][j-1]);
}
for (int j = 0; j <= min(n,q); j++) {
if (dp[n][j] != 1e9) {
r = w-1;
goto skip;
}
}
l = w+1;
skip:;
}
cout << l << endl;
}
