#!/usr/bin/env python3

import math


EPS = 1e-16


def compute_point(n, k):
    return 50 * n + math.floor(50 * n / (0.8 + 0.2 * k + EPS))


def main():
    a, b = (int(x) for x in input().split())
    print(compute_point(a, b))


if __name__ == '__main__':
    main()