n = int(input())
l = []
for i in range(n):
    a = input().split()
    if a[0] == 'push':
        l.insert(0,a[1])
    elif a[0] == 'pop' and len(l) != 0:
        print(l.pop())
    elif a[0] == 'front' and len(l) != 0:
        print(l[-1])
    else:
        print('error')