N = int(input())
A = list(map(int, input().split()))
memo = [(a, i) for i, a in enumerate(A)]

ans = 0
x = 0
for a, i in memo:
    if a == 0:
        continue
    a -= 1
    while a and x < N:
        if not A[x]:
            A[x] += 1
            ans += abs(x - i)
            x += 1
        else:
            x += 1
    A[i] = 1

print(ans)