import sys
from pprint import pprint

def topological_sort_visit(graph, node, node_list):
    if node in graph:
        if graph[node]['mark'] == 2:
            return
        
        if graph[node]['mark'] == 1:
            # there are cycles in our graph. don't go down this path
            return
            
        graph[node]['mark'] = 1
        for child in graph[node]['children']:
            topological_sort_visit(graph, child, node_list)

        graph[node]['mark'] = 2

    # since there are cycles, check presence before adding
    if node not in node_list:
        node_list.append(node)

def topological_sort(graph):
    nodes = []
    for key in graph.keys():
        topological_sort_visit(graph, key, nodes)
    return nodes

graph = {}

# The input represents a Source -> Destination mapping
for line in sys.stdin.read().strip().split('\n'):
    [src, dest] = line.replace("'", "").split(':')
    if src not in graph:
        graph[src] = {'children': [dest], 'mark': 0}
    else:
        graph[src]['children'].append(dest)

sorted_list = topological_sort(graph)
pprint(sorted_list)