못생긴 수

p. 381

 

n=int(input())

i2=i3=i5=0

next2=2
next3=3
next5=5

d=[0]*n

d[0]=1

for i in range(1,n):
  d[i]=min(next2,next3,next5)
  if d[i]==next2:
    i2+=1
    next2=d[i2]*2
  if d[i]==next3:
    i3+=1
    next3=d[i3]*3
  if d[i]==next5:
    i5+=1
    next5=d[i5]*3

print(d[n-1])