N = int(input())
P = list(map(int, input().split()))

total = 0
used = set()
for i in range(N-1, -1, -1):
    p = P[i]
    if p != N and p+1 not in used:
        total += i+1
        used.add(p+1)
    elif p not in used:
        used.add(p)
    else:
        total -= i+1
        for j in range(1, N):
            if j not in used:
                used.add(j)
                break
print(total)