while 1:
    try:
        s = input().split()
        n = s[0]
        head = s[1]
        out = s[-1]
        info = s[2:-1]
        node = []
        #print(info)
        #print(len(info)/2)
        for i in range(int(len(info)/2)):
            #print(info[2*i+1])
            node.append((info[2*i],info[2*i+1]))
            #node.append(tuple(info[2*i],info[2*i+1]))
        #print(node)
        result = []
        #print(node[1][1])
        for k in range(len(node)):
            #print(node[k][1])
            if node[k][1] not in result:
                result.append(node[k][1])
                result.append(node[k][0])
            elif node[k][1] in result:
                ind = result.index(node[k][1])
                #print(ind,'ind')
                result.insert(ind+1,node[k][0])
#             if node[k][1] not in result:
#                 print(node[k][1])
#                 result.append(node[k][1],node[k][0])
       # print(result)
        result.remove(out)
        print(*result)
     
    except:
        break