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


LIST=[]
for i in range(1,len(A)):
    LIST.append(A[i]-A[i-1]-1)

ANS=M

while LIST:
    if LIST[-1]<=1:
        LIST.pop()
    elif LIST[-1]%2==0:
        LIST.pop()
    else:
        k=LIST[-1]
        ANS+=1
        LIST.pop()

        l=k//2
        LIST.append(l)
        LIST.append(l)

print(N-ANS)