def main():
    n = int(input())
    a = list(map(int,input().split()))
    rec = [0 for i in range(n)]
    for i in range(n):
        rec[i] = (i + 1) * (n - i)

    ans = 0
    for i in range(n):
        ans += rec[i] * a[i]

    print(ans)
main()