＃i nclude <iostream>
＃i nclude <cstdio>
＃i nclude <cstring>
using namespace std;

int num2,num3,num5,num7,num9,n,m;
int tab[4][4]=
{
    6,2,4,8,
    1,3,9,7,
    1,7,9,3,
    1,9,1,9
};
int get2(int x)
{
    if (x==0) return 0;
    return x/2+get2(x/2);
}
int get5(int x)
{
    if (x==0) return 0;
    return x/5+get5(x/5);
}
int g(int x,int y)
{
    if (x==0) return 0;
    return x/10+(x%10>=y)+g(x/5,y);
}
int get(int x,int y)
{
    if (x==0) return 0;
    return get(x/2,y)+g(x,y);
}

int main()
{
    while (scanf("%d%d",&n,&m)!=EOF)
    {
        num2=get2(n)-get2(n-m);
        num5=get5(n)-get5(n-m);
        num3=get(n,3)-get(n-m,3);
        num5=get(n,5)-get(n-m,5);
        num7=get(n,7)-get(n-m,7);
        num9=get(n,9)-get(n-m,9);
        if (num2<num5)
        {
            puts("5");
            continue;
        }
        num2-=num5;
        int ans=1;
        if (num2>0) ans*=tab[0][num2%4];
        ans*=tab[1][num3%4];
        ans*=tab[2][num7%4];
        ans*=tab[3][num9%4];
        printf("%d\n",ans%10);
    }
    return 0;
}