#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;
#define DEBUG 1
#define ll long long
#define gc getchar_unlocked
void scanint(ll int &x)
{
register int c = getchar_unlocked();
x = 0;
int neg = 0;
for(;((c<48 || c>57) && c != '-');c = gc());
if(c=='-') {neg=1;c=gc();}
for(;c>47 && c<58;c = gc()) {x = (x<<1) + (x<<3) + c - 48;}
if(neg) x=-x;
}
ll int max ( ll int a , ll int b ) {
return a > b ? a : b;
}
int main ( int argc , char * argv[] ) {
ll int t , z;
ll int a , b;
ll int sum = 0;
scanint(t);
scanint(a);
for ( z = 2 ; z <= t ; z++ ) {
scanint(b);
sum += max(a,b);
a = b;
}
printf("%lld\n" , sum);
return 0;
}
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