from math import log2,floor,ceil
x,y,h = map(int,input().split())
x *= 1000
y *= 1000
l = ceil(log2(x/h))
r = ceil(log2(y/h))
lup = floor(log2(x/h)+2)
rup = floor(log2(y/h)+2)
lis1 = [i for i in range(l,lup)]
lis2 = [i for i in range(r,rup)]
ans = 0
for p in lis1:
    for q in lis2:
        a = 2*p-q
        b = 2*q-p
        if a%3!=0 or b%3 != 0:continue
        else:
            a //=3;b//=3
            if a >= 0 and b >= 0:
                ans = max(ans,a+b)
print(ans)