#include<bits/stdc++.h>
using namespace std;
typedef long double ld;
typedef long long ll;
#define rep(a, b) for(int a = 0; a < (b); ++a)
#define st first
#define nd second
#define pb push_back
#define all(a) a.begin(), a.end()
const ll INF=1e9+7;
const int LIM=1e3+7;
ll T[LIM], n, k, t;
ll odw[LIM][LIM], dp[LIM][LIM];
ll solve(ll l, ll r, ll x) {
if(odw[l][r]) return dp[l][r];
odw[l][r]=1;
dp[l][r]=-INF;
if(l>r || r<k || k<l) return dp[l][r];
ll a=solve(l+1, r, x), b=solve(l, r-1, x);
if(a>=T[l+1]-T[l]) dp[l][r]=max(dp[l][r], a-T[l+1]+T[l]+t*x*2);
if(b>=T[r]-T[r-1]) dp[l][r]=max(dp[l][r], b-T[r]+T[r-1]+t*x*2);
return dp[l][r];
}
bool check(ll x) {
rep(i, n) rep(j, n) odw[i][j]=dp[i][j]=0;
dp[k][k]=2*x*t;
odw[k][k]=1;
return solve(0, n-1, x)>=0;
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> k >> t; --k;
rep(i, n) cin >> T[i];
ll po=0, ko=INF;
while(po<ko) {
ll sr=(po+ko)/2;
if(check(sr)) ko=sr; else po=sr+1;
}
cout << po << '\n';
}
