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

ans = 0
for i in range(N):
    for j in range(i+1,N):
        if min(A[i],A[j]) >= 2:
            ans += 1
        elif max(A[i],A[j])-min(A[i],A[j]) > 1:
            ans += min(A[i],A[j])+1
        else:
            ans += max(A[i],A[j])+1

print(ans)