using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

    int a,b;

        int[] c = Console.ReadLine().Split().Select(int.Parse).ToArray();

    int[] d = new int[]{7,6,5,6,7,8,9,10,11,12,13,14,15,20,21};

    //int[] d = Console.ReadLine().Split().Select(int.Parse).ToArray();

    a=d[0]+d[1]*(c[2]-c[0]);

    b=1;

        for(int i = 2;i<=14;i++){

        b=b*(c[2]-c[0]-c[1]*(i-1));

    a=a+d[i-1]*b;

    }

    Console.WriteLine(a);   

    }

}

​