#include<bits/stdc++.h>
#define pb push_back
#define fi first
#define se second
#define mp make_pair
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef long double ld;
template <typename T> bool chkmin(T &x,T y){return x>y?x=y,1:0;}
template <typename T> bool chkmax(T &x,T y){return x<y?x=y,1:0;}
int readint(){
int x=0,f=1; char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
return x*f;
}
int n,m,k,a[20005];
ll dp[20005];
int main(){
n=readint(); m=readint(); k=readint();
for(int i=1;i<=n;i++) a[i]=readint();
for(int i=1;i<=n;i++){
dp[i]=1e18;
int mn=a[i],mx=a[i];
for(int j=i;j>max(0,i-m);j--){
mn=min(mn,a[j]);
mx=max(mx,a[j]);
dp[i]=min(dp[i],dp[j-1]+k+(i-j+1)*1ll*(mx-mn));
}
}
printf("%lld\n",dp[n]);
return 0;
}
