import sys
sys.setrecursionlimit(0x10000000)


def add(a, b):
    g[a].append(b)
    g[b].append(a)


def bfs(st):
    q = []
    q.append(st)
    used[st] = True
    while len(q) != 0:
        v = q.pop(0)
        for i in g[v]:
            if not used[i]:
                used[i] = True
                q.append(i)
                parent[i] = v
                d[i] = d[v] + 1


n = int(input())
used = [False] * (n + 10)
parent = [-1] * (n + 10)
d = [0] * n
g = []
for i in range(n):
    g.append([])
for i in range(n):
    l = list(map(int, input().split()))
    for j in range(i + 1, n):
        if l[j] == 1:
            add(i, j)
st, en = list(map(int, input().split()))
bfs(st - 1)
if not used[st - 1]:
    print(-1)
else:
    path = []
    v = en - 1
    while v != -1:
        path.append(v + 1)
        v = parent[v]
print(len(path) - 1)
print(*reversed(path))