import sys

#N = int(input())
N = int(sys.stdin.readline())
lst1 = []
lst2 = []
ans = ''
for i in range(N):
  #T,S = input().split(' ')
  T,S = sys.stdin.readline().strip().split(' ')
  if T == '0':
    #ans += S
    lst1.append(S)
  else:
    #ans = S + ans
    lst2.append(S)
#print(ans)
print(''.join(lst2[::-1]) + ''.join(lst1))