#include <stdio.h>

int main(void)
{
	int a;
	int b;
	int q;
	int w;
	int ac;
	scanf("%d%d",&a,&b);
	q=50*a;
	ac=q+50*a/(0.8+0.2*b);
	printf("%d\n",ac);
	return 0;
}