#include <stdio.h>

int main() {
	int c, d;
	scanf("%d %d", &c, &d);

	double a, b, ca, da, cb, db;

	if (c * 5 <= d * 2) {
		a = 0.0;
		b = c + c * 2.5;
	}
	else if (c >= d * 3) {
		a = d * 3.0 + d;
		b = 0.0;
	}
	else {
		ca = (c * 15.0 - d * 6.0) / 13.0;
		da = ca / 3.0;
		cb = c - ca;
		db = d - ca / 3.0;
		a = ca + da;
		b = cb + db;
	}

	double ans = a * 1000 + b * 2000;
	
	printf("%.7lf\n", ans);
	return 0;
}