int input 30001 for in range map int input split min if abs a-b and ab

n = int(input())
s = 0
l = 30001
for i in range(n):
    a, b = map(int, input().split())
    s += min(a, b)
    if abs(a-b) < l and abs(a-b) % 4 != 0:
        l = abs(a-b)
if s % 4 == 0:
    s += l
    if l == 30001:
        print("no")
    else:
        print(s)
else:
    print(s)