def inp() a=gets.chomp.split(" ").map(&:to_i)end 
def inpf() a=gets.chomp.split(" ").map(&:to_f)end
def inps() a=gets.chomp.split(" ")end  
def copy(a) Marshal.load(Marshal.dump(a)) end
def kaizyo(n)(n < 2)? 1 : (2..n).inject(:*) end
def scount(a,b) a.each{|n|b[n]+=1} end
def na(n,d=0) Array.new(n,d)end
def na2(n,m,d=0) Array.new(n){Array.new(m,d)}end
def na3(n,m,l,d=0) Array.new(n){Array.new(m){Array.new(l,d)}}end
sosu = "2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101,
103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,
199,211,223,227,229,233,239,241,251,257,263,269,271,277,281,283,293,307,311,
313,317,331,337,347,349,353,359,367,373,379,383,389,397,401,409,419,421,431,
433,439,443,449,457,461,463,467,479,487,491,499,503,509,521,523,541,547,557,
563,569,571,577,587,593,599,601,607,613,617,619,631,641,643,647,653,659,661,
673,677,683,691,701,709,719,727,733,739,743,751,757,761,769,773,787,797,809,
811,821,823,827,829,839,853,857,859,863,877,881,883,887,907,911,919,929,937,
941,947,953,967,971,977,983,991,997"
sosu = sosu.delete("\n").split(",").map(&:to_i)
n = inp[0]
dp = na2(2,20001,nil)
dp[0][0] = 0
max = 0
sosu.each_with_index do |d,i|
  (0..20000).each do |m|
    break if(m > n-d)
    break if(m > max)
    if(dp[(i)%2][m] != nil)
      dp[(i+1)%2][m+d] = dp[i%2][m]+1  if(m+d < 20001) if(dp[(i+1)%2][m+d] == nil or dp[i%2][m]+1 > dp[(i+1)%2][m+d])
      dp[(i+1)%2][m] = dp[i%2][m]
    end
  end
  max = max+d
end
p (dp[sosu.size%2][n] == nil)? -1 : dp[sosu.size%2][n]