L=sorted(map(int,input().split()))

c=L[0]
L=[i-c for i in L]

m=(L[2]-L[1])//2
L=[m,L[1],L[2]-m*2]

c+=L[0]
L=[i-m for i in L]

m=L[1]//2
L=[m,L[1]-m,L[2]-m]

c+=L[0]
L=[i-m for i in L]
print(c)