import java.io.*;
import java.util.*;

class Main
{
    public static void main(String args[])throws Exception
    {
        BufferedReader bu=new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb=new StringBuilder();
        String s[]=bu.readLine().split(" ");
        int p=Integer.parseInt(s[0]),q=Integer.parseInt(s[1]),r=Integer.parseInt(s[2]);
        int ans[][]=power(Long.parseLong(s[3])-4);
        int f[][]={{r%M},{q%M},{p%M}};
        ans=multiply(ans,f);
        System.out.println(ans[0][0]);
    }

    static int M=10;
    static int[][] power(long n)
    {
        int a[][]={{1,1,1},{1,0,0},{0,1,0}},res[][]=new int[3][3];
        int i;
        for(i=0;i<3;i++) Arrays.fill(res[i],1);

        while(n!=0)
        {
            if(n%2==1) res=multiply(res,a);
            n>>=1;
            a=multiply(a,a);
        }
        return res;
    }

    static int[][] multiply(int a[][],int b[][])
    {
        int i,j,k,ans[][]=new int[a.length][b[0].length];
        //System.out.println(a.length+" "+a[0].length+" "+b.length+" "+b[0].length);
        for(i=0;i<a.length;i++)
        for(j=0;j<b[0].length;j++)
        for(k=0;k<a[0].length;k++)
        ans[i][j]=(ans[i][j]+a[i][k]*b[k][j]%M)%M;
        return ans;
    }
}