№15 — #15128

d = []
for a in range(0, 200):
    if all(((4 * x + 3 * y >= 70) <= (x + y >= a)) and ((x + y >= a) <= (2 * x + 1 * y >= 20)) for x in range(0, 200) for y in range(0, 200)) == 1:
        d.append(a)
d.sort()
print(min(d))