# -*- coding: utf-8 -*-

from math import floor


def check_score(N, K):
    score_1 = 50 * N
    score_2 = score_1 * 10 / (8 + 2 * K)
    return score_1 + floor(score_2)


n, k = map(int, input().split())
print(check_score(n, k))