#include <bits/stdc++.h>
using namespace std;
int main() {
int n, k, t;
cin >> n >> k >> t;
k--;
int x[n];
for(int i=0;i<n;i++)
cin >> x[i];
int l = -1, h = (1e9 / t) + 1;
while(h - l > 1) {
int s = (l + h) / 2;
int d = s * t;
bool reach[n][n];
memset(reach,0,sizeof(reach));
reach[k][k] = 1;
for(int l=k;~l;l--)
for(int r=k;r<n;r++)
if(reach[l][r]) {
if(r+1<n && x[r+1] - x[l] <= 2LL * (r - l + 1) * d)
reach[l][r+1] = 1;
if(l && x[r] - x[l-1] <= 2LL * (r - l + 1) * d)
reach[l-1][r] = 1;
}
if(reach[0][n-1])
h = s;
else
l = s;
}
cout << h;
}
