#include "stdio.h"
void main()
{
int workyears,workhours;
float salary;
scanf("%d %d",&workyears,&workhours);
if (workyears >=5)
{
if (workhours >40)
salary = 4050 + (workhours-40)501.5;
else
salary = workhours * 50;
}
else
{ if (workhours >40)
salary = 4030 + (workhours-40)301.5;
else
salary = workhours * 30;
}
printf("%.2f\n",salary);
}