360笔试，下午场

while True:
    try:
        s = input()
        if s==s[::-1]:
            n = len(s)
            flag = True
            res = ['A','H','I','M','O','T','U','V','W','X'.'Y']
            for i in range(n//2+1):
                if s[i] not in res:
                    flag = False
                    break
            if flag==True:
                print('YES')
            else:
                print('NO')
        else:
            print('NO')
    except:
        break

n = int(input())
list1 = []
list2 = []
for i in range(n):
    nums = list(map(int,input().split()))
    if nums[1]==0:
        list1.append(nums)
    else:
        list2.append(nums)
list2 = sorted(list2,reverse=True)
sum1 = 0 
for key in list1:
    sum1+=key[0]
for key in list2:
    if sum1+key[0]>sum1*2:
        sum1+=key[0]
    else:
        sum1*=2
print(sum1)