#include<cstdio>#include<cstring>#include<algorithm>using namespace std;int dp[410][410],val[410],s[410],INF=1e9;int main(){ int n,N,i,j,k,len,ans; double p; while(~scanf("%d%lf",&n,&p) && n) { for(i=1;i<=n;i++) { scanf("%d",&val[i]); val[i+n]=val[i]; } N=n*2; for(i=1;i<=N;i++) { dp[i][i]=0; s[i]=s[i-1]+val[i]; } for(len=1;len<n;len++) for(i=1;i+len<=N;i++) { j=i+len; dp[i][j]=INF; for(k=i;k<j;k++) dp[i][j]=min(dp[i][j],dp[i][k]+dp[k+1][j]+max(s[k]-s[i-1],s[j]-s[k])); } ans=INF; for(i=1;i<=n;i++) ans=min(ans,dp[i][i+n-1]); printf("%.2fn",ans*p); }}
