#include <stdio.h>

int f(double a, double b) {
	return 50 * a + (int)((50 * a) / (0.8 + 0.2 * b));
}

int main() {
	double a, b;

	scanf("%lf %lf", &a, &b);
	printf("%d\n", f(a, b));

	return 0;
}