#include <cstdio>

using namespace std;

int main()
{
    freopen("koba.in","r",stdin);
    freopen("koba.out","w",stdout);
    int n,t1,t2,t3,tf,i;
    long long sol=0;
    scanf("%d%d%d%d",&n,&t1,&t2,&t3);
    sol=t1%10+t2%10+t3%10;
    for(i=4;i<=n;i++)
    {
        tf=(t3+((t2%10)*(t1%10)))%10;
        t1=t2;
        t2=t3;
        t3=tf;
        sol+=tf%10;
    }
    printf("%lld",sol);
}