#include<bits/stdc++.h> using namespace std; long long n,a[1000006],sum; int main(){ //freopen("legion.in","r",stdin); //freopen("legion.out","w",stdout); scanf("%lld",&n); for(int i=1;i<=n;i++){ scanf("%lld",&a[i]); if(i!=1){ sum+=max(a[i],a[i-1]); } } printf("%lld",sum); }