import sys
input = sys.stdin.readline

N = int(input())
A = list(map(int, input().split()))
even = [10**20]
odd = [10**20]
for a in A:
    if a % 2 == 0:
        even.append(a)
    else:
        odd.append(a)
even.sort()
odd.sort()
cnt_even = {}
cnt = 1
for i in range(len(even) - 1)[::-1]:
    if even[i+1] == even[i] + 2:
        cnt += 1
    else:
        cnt = 1
    cnt_even[even[i]] = cnt
cnt_odd = {}
cnt = 1
for i in range(len(odd) - 1)[::-1]:
    if odd[i+1] == odd[i] + 2:
        cnt += 1
    else:
        cnt = 1
    cnt_odd[odd[i]] = cnt
ans = N
for a in A:
    if a % 2 == 0:
        if a + 1 in cnt_odd:
            ans += cnt_odd[a + 1]
    else:
        if a + 1 in cnt_even:
            ans += cnt_even[a + 1]
print(ans)