#include<fstream>
using namespace std;
ifstream fin("koba.in");
ofstream fout("koba.out");
long long t1,t2,t3,n,i,x,y,z,sum,r;
int main(){
    fin>>n>>t1>>t2>>t3;
    x=t1%10;
    y=t2%10;
    z=t3%10;
    sum+=(x+y+z);
    for(i=4;i<=n;i++){
        r=0;
        r=(z+x*y)%10;
        sum+=r;
        x=y;
        y=z;
        z=r;
    }
    fout<<sum;
    return 0;
}