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def ShortestPath(strArr):
    places = {}
    nPlaces = int(strArr[0])
    for i in range(1, nPlaces + 1):
        places[strArr[i]] = {
            'name': strArr[i],
            'path': '',
            'routes': {}
        }
    for i in range(nPlaces + 1, len(strArr)):
        route = strArr[i].split('-')
        places[route[0]]['routes'][route[1]] = places[route[1]]
        places[route[1]]['routes'][route[0]] = places[route[0]]
    start = places[strArr[1]]
    finish = places[strArr[nPlaces]]
    start['path'] = start['name']
    pending = [start]
    while pending:
        here = pending.pop(0)
        if here == finish:
            return finish['path']
        for place in here['routes']:
            if here['routes'][place]['path'] == '':
                next_place = here['routes'][place]
                next_place['path'] = here['path'] + '-' + next_place['name']
                pending.append(next_place)
    return -1

# Example usage
import sys
print ShortestPath(sys.stdin.readline().split())