#include <stdio.h>

int main()
{
FILE *in = fopen("koba.in","r");
FILE *out = fopen("koba.out","w");

int n,t1,t2,t3,x,s;

fscanf(in,"%d%d%d%d",&n,&t1,&t2,&t3);

t1 = t1%10;
t2 = t2%10;
t3 = t3%10;
s = t1+t2+t3;

n=n-3;

while (n)
{
n--;
x = t3+t2*t1;
t1 = t2;
t2 = t3;
t3 = x%10;
s += t3;
}
fprintf(out,"%d",s);
}