difference = list()
summa = 0
for i in range(int(input())):
    a, b = map(int, input().split())
    if a < b:
        summa += a
    else:
        summa += b
    difference.append(abs(a-b))
print(f'summa = {summa}')
to_add_for_end_is_7 = 7 - summa % 10
print(f'need to add something that ends with {to_add_for_end_is_7}')
difference.sort()
for i in difference:
    if i % 10 == to_add_for_end_is_7:
        print(f'can add {i}')
        print('otvet = ', summa + i)  # file a and b answers  8317 19596697
        break

''''
5
1 3
5 11
6 9
5 4
5 7
'''