#include <bits/stdc++.h>
using namespace std;
#define int long long 
const int maxm = 23;
const int maxn=100005;
int dp[(1<<maxm) + 5];
const int oo = 1'000'000'000'000'000'000ll;
int n,m,k;
int S[maxn];
int F[maxm][maxm];
int B[maxm][maxm];
int32_t main(){
	for(int i=1;i<1<<m;i++)dp[i]=oo;
	cin >> n >> m >> k;
	for(int i=1;i<=n;i++){
		cin>>S[i];
		--S[i];
	}
	for(int i=1;i<=n-1;i++){
		F[S[i]][S[i+1]]++;
		B[S[i+1]][S[i]]++;
	}
	for(int bm=0;bm<1<<m;bm++){
		vector<int>on,off;
		for(int i=0;i<m;i++){
			if(bm&(1<<i)){
				on.push_back(i);
			} else{
				off.push_back(i);
			}
		} 
		for(auto x:off){
			int pos = on.size() + 1;
			int nbm=bm|(1<<x);
			int res=dp[bm];
			for(int b=0;b<m;b++){
				if(b==x)continue;
				if(bm&(1<<b)){
					res += k * F[x][b] * pos;
				} else{
					res += F[x][b] * (-pos);
				}
			}
			for(int b=0;b<m;b++){
				if(b==x)continue;
				if(bm&(1<<b)){
					res += B[x][b] * pos;	
				} else{
					res += B[x][b] * pos * k;
				}
			}
			dp[nbm]=min(dp[nbm],res);
		}
	}
	cout<<dp[(1<<m)-1];
}