N = int(input())
B = list(map(int, input().split()))
lack = 0
ans = 0

for Bi in B:
    ans += abs(lack)
    
    if lack>=0 and Bi==0:
        lack += 1
    elif lack>=0 and Bi>0:
        lack -= Bi-1
    elif lack<0 and Bi==0:
        lack += 1
    elif lack<0 and Bi>0:
        lack -= Bi-1

print(ans)