#include <iostream>
#include <cstring>
using namespace std;
#define ll long long
#define INF 1e16
int n, m, k;
ll arr[20001], dp[20001];
ll go(int pos)
{
if(pos == n)
return 0;
ll& ret = dp[pos];
if(ret != -1)
return ret;
ret = INF;
ll mx = arr[pos], mn = arr[pos];
for(int i = pos; i < min(n, pos+m); i++)
{
mx = max(mx, arr[i]);
mn = min(mn, arr[i]);
ret = min(ret, (i-pos+1)*(mx-mn)+k + go(i+1));
}
return ret;
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
memset(dp, -1, sizeof(dp));
cin >> n >> m >> k;
for(int i = 0; i < n; i++)
cin >> arr[i];
cout << go(0) << '\n';
}
