C = list(map(int, input().split()))
ans = 0
ans += min(C)
C = list(map(lambda x: x-ans, C))
C.sort(reverse=True) #descending
while C.count(0)==1:
    temp = min(C[0]//3, C[1])
    C[0] -= temp*3
    C[1] -= temp
    ans += temp
    C.sort(reverse=True) #descending
    
while C.count(1)==2:
    ans += C[0]//5

print(ans)