#include <stdio.h>

#define in "koba.in"
#define out "koba.out"

int T1, T2, T3;
int N;
int S, X, Y, Z;

int main()
{
    freopen( in, "r", stdin );
    freopen( out, "w", stdout );
    
    scanf( "%d%d%d%d", &N, &T1, &T2, &T3 );
    
    int i;
    S = 0;
    for ( i = 1; i <= N; ++i )
    {
        if ( i == 1 ) { S += T1 % 10; }
        else if ( i == 2 ) { S += T2 % 10; }
        else if ( i == 3 ) { S += T3 % 10; } 
        else
        {
            X = T3 % 10;
            Y = T2 % 10;
            Z = T1 % 10;
            Y *= Z;
            Y %= 10;
            S += ( (X + Y) % 10 );
            T1 = T2;
            T2 = T3;
            T3 = (X + Y) % 10;
        }
    }
    printf( "%d\n", S );
    return 0;
}