#include "stdio.h"
int main()
{
    float money;
    float k1;
    int year, hour;
    scanf("%d %d", &year, &hour);
    if (year < 5)
        k1 = 30;
    else
        k1 = 50;

    if (hour > 40)
        money = 40 * k1 + (hour - 40) * k1 * 1.5f;
    else
        money = hour * k1;

    printf("%.2f", money);
    return 0;
}