#55361: C++ new sol
11430435@mail.hpsh.tp.edu.tw
(吳宥霖11319)
#include <bits/stdc++.h>
using namespace std;
int main() {
int n,ans=0;
int h[102]={0};
cin>>n;
h[0]=101;
h[n+1]=101;
for(int i=1;i<=n;i++){
cin>>h[i];
}
for(int i=1;i<=n;i++){
if(!h[i]){
ans+=min(h[i-1],h[i+1]);
}
}
cout<<ans;
return 0;
}