R,G,B=map(int,raw_input().split())
left = 0
right = 10000000
while left+1 < right:
    mid = (left+right)/2
    rest = 0
    if R>mid:
        rest += (R-mid)/2
    else:
        rest-=(mid-R)
    if G>mid:
        rest += (G-mid)/2
    else:
        rest-=(mid-G)
    if B>mid:
        rest += (B-mid)/2
    else:
        rest-=(mid-B)
    if rest >= 0:
        left = mid
    else:
        right =mid
print left