#include <stdio.h>
using namespace std;
int v[4],sum,n,a;
int main()
{
    freopen("koba.in","r",stdin);
    freopen("koba.out","w",stdout);
    scanf("%d%d%d%d",&n,&v[1],&v[2],&v[3]);
    sum=v[1]%10+v[2]%10+v[3]%10;
    n-=3;
    while(n)
    {
        v[1]%=10;
        v[2]%=10;
        v[3]%=10;
        a=v[3]+v[2]*v[1];
        a%=10;
        sum+=a;
        v[1]=v[2];
        v[2]=v[3];
        v[3]=a;
        n--;
    }
    printf("%d",sum);
    return 0;
}