def parse(inFile):
    N = inFile.getInt()
    return [[z - 1 for z in inFile.getInts()[1:]] for k in xrange(N)]

def solve(dependents):
    N = len(dependents)
    for i in xrange(N):
        dep = [False] * N
        q = [i]
        while (len(q)):
            for j in dependents[q.pop()]:
                if (dep[j]):
                    return "Yes"
                dep[j] = True
                q.append(j)
    return "No"

if __name__ == "__main__":
    from GCJ import GCJ
    GCJ(parse, solve, "/Users/lpebody/gcj/setup/", "a").run()