from collections import *

N = int(input())
A = list(map(int, input().split()))
E, O = [], []
for a in A:
    if a % 2:
        O.append(a)
    else:
        E.append(a)
O.sort(reverse=True)
E.sort(reverse=True)
D = defaultdict(int)
now = 1
pre = -1
for od in O:
    if od == pre - 2:
        now += 1
    else:
        now = 1
    D[od - 1] += now
    pre = od
    
now = 1
pre = -1
for ev in E:
    if ev == pre - 2:
        now += 1
    else:
        now = 1
    D[ev - 1] += now
    pre = ev
    
ans = N
for a in A:
    ans += D[a]
print(ans)