import sys
input = sys.stdin.readline
from collections import *

N = int(input())
P = list(map(int, input().split()))
flag = [False]*N
ans = 0

for i in range(N-1, -1, -1):
    P[i] -= 1
    
    if P[i]==N-1:
        if flag[N-1]:
            ans -= i+1
        else:
            flag[N-1] = True
    else:
        if flag[P[i]+1]:
            if flag[P[i]]:
                ans -= i+1
            else:
                flag[P[i]] = True
        else:
            flag[P[i]+1] = True
            ans += i+1

print(ans)