using System;
using System.Linq;

class Program {
    public static void Main() {
        int[] a = new int[9];
        int n = int.Parse(Console.ReadLine());
        while (n > 0) {
            if (n % 10 == 9) a[6]++;
            else a[n % 10]++;
            n /= 10;
        }
        a[6] = (a[6] + 1) / 2;
        Console.Write(a.Max());
    }
}