a = int(input())
b=0
c=0
if a<=1:
    print(0)
else:
    for num in range(2,a+1):   
        if c>a:
            break
        elif num>1:
            for i in range(2,num):
                if num%i==0:
                    break
            else:
                if c+num<=a:
                    b=b+1
                    print(num)
                    c=c+num
    print(b)