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OI-codes/Luogu/P4445/P4445.cpp

18 lines
298 B
C++

#include <bits/stdc++.h>
using namespace std;
int main() {
int n, a[100005];
long long ans = 0;
cin >> n;
for (int i = 0; i < n; i++) {
cin >> a[i];
}
for (int i = 1; i < n; i++) {
ans += max(a[i], a[i - 1]);
}
cout << ans << endl;
return 0;
}