N = int(input())

from collections import defaultdict

A = list(map(int, input().split()))
A.sort()
D = defaultdict(int)

for a in A:
    D[a] += 1


ans = N

for a in A:
    
    ans += D[a - 1]
    
    D[a + 1] += D[a - 1]
    
print(ans)