X,Y,Z = map(int,input().split())

if X > Y:
    diff = X-Y
    if Z >= diff:
        Y += diff
        X += (Z-diff)//2
        Y += (Z-diff)//2
    else:
        Y += Z
else:
    diff = Y-X
    if Z >= diff:
        X += diff
        X += (Z-diff)//2
        Y += (Z-diff)//2
    else:
        X += Z

print(min(X,Y))