b294. 經濟大恐荒 -- 板橋高中 教學題 | From: [27.109.151.69] | 發表日期: 2023-04-13 19:22

c = int(input())
l = list(map(int, input().strip().split()))
sum = 0
for n in range(0, c):
  sum += (n + 1)*l[n]
print(sum)