nodes = list()
N = int(input())
for i in range(N):
    nodes.append(list(map(int, input().split())))
S, F = map(int, input().split())
dist = [-1] * N


def DFS(N, S, F, nodes):
    global dist
    dist[S - 1] = 0
    stack = [S - 1]
    prev = [-1] * N
    way = list()
    way.append(F)
    while stack:
        v = stack.pop(0)
        for i in range(N):
            if i == F + 2:
                break
            if nodes[v][i] == 1 and dist[i] == -1:
                stack.append(i)
                dist[i] = dist[v] + 1
                prev[i] = v + 1
    if dist[F - 1] == -1:
        print(-1)
    else:
        print(dist[F - 1])
    while F != S:
        F = prev[F - 1]
        way.append(F)
    print(*way[::-1])


DFS(N, S, F, nodes)