#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int n, k;
ll t;
bool v[1001][1001];
ll pos[1001];
// ll dp[2][1000][1000];
// ll pos[1000];
bool go(int l, int r){
if((pos[r]-pos[l]>2LL*t*(ll)(r-l))){
return false;
}
if(v[l][r]){
return false;
}
if(l==0 && r==n-1){
return true;
}
v[l][r] = true;
if(l>0 && go(l-1,r)){
return true;
}
if(r<n-1 && go(l,r+1)){
return true;
}
return false;
}
int main(){
ll tt;
cin >> n >> k >> tt;
for(int i = 0; i<n; i++){
cin >> pos[i];
}
k--;
ll low = 0LL;
ll high = 1000000000LL;
while(low<high){
ll mid = (low+high)/2LL;
t = mid*tt;
for(int a = 0; a<1; a++){
for(int b = 0; b<n; b++){
for(int c = 0; c<n; c++){
v[b][c] = false;
}
}
}
// cout << "! " << low << " " << high << " " << t << " " << endl;
if(go(k,k)){
// cout << "A " << endl;
high = mid;
}
else{
// cout << "B " << endl;
low = mid+1;
}
}
cout << low << endl;
}
