#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vll = vector<ll>;
using vi = vector<int>;
using vvll = vector<vll>;
using vvi = vector<vi>;
#define sz(x) int(x.size())
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
ll N, K, T;
cin >> N >> K >> T;
vll X(1+N);
for(int i = 1; i <= N; i++)
{
cin >> X[i];
}
ll lo = 1, hi = ((((1'000'000'000'000'000'000LL / 2LL + 1) / N) + 1) / T) + 1;
// ll lo = 1, hi = 1'000'000'000'000'000'000LL/N;
while(lo != hi)
{
ll mid = (lo + hi)/2;
vvll dp(1+N, vll(1+N, 0));
// for(ll l = N; l >= 1; l--)
for(ll d = 0; d <= N-1; d++)
{
for(ll l = 1; l+d <= N; l++)
{
ll r = l+d;
if(l == r && r == K)
dp[l][r] = 1;
else if(2LL * T * (r-l) * mid < X[r] - X[l])
// else if(2LL * (r-l) * mid < X[r] - X[l])
dp[l][r] = 0;
else if(l < r)
dp[l][r] = dp[l+1][r] || dp[l][r-1];
}
}
if(dp[1][N] == 1)
hi = mid;
else
lo = mid+1;
}
cout << lo << '\n';
}
