N=int(input());H=sorted(map(int,input().split()))[:60];o,n=120,0
while o-n>1:
    p=1<<(m:=(o+n)>>1);Q=H[:]
    while p:=p>>1:Q[-1]-=p;Q.sort()
    if Q[-1]>0:n=m
    else:o=m
print(o+(N-len(H)))