def mex(a,b):
  num = 0
  if a == 1:
    if b == 2:
        num = b+1
    else:
        num = 2
  else:
    num = a-1
  return num

N = int(input())
A = list(map(int,input().split()))
A.sort()
c1 = A.count(1)
ans = max(0,c1*(c1-1))
num = A[0]
for i in range(c1,N):
  ans += (mex(num,A[i])*c1)
ans += max(0,(N-c1)*(N-c1-1)//2)

print(ans)