#include <bits/stdc++.h>

using namespace std;

int a[10000005], n, ans = 0, k;
int main() {
    cin >> n;
    for (int i = 1; i <= n; ++i)
    {
        cin >> a[i];
    }
    for (int i = 1; i <= n; ++i)
    {
        ans += a[i] * i;
    }
    cout << ans;
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int a[10000005],n;
int main() {
    cin>>n;
    long long kq= 0;
    for (int i=1;i<=n;++i) {
        cin>>a[i];
        kq+=a[i]*i;
    }
    cout<<kq;
}