MOD = 998244353

def inverse(n, d):
    return n * pow(d, -1, MOD) % MOD

def matrix(a, b):
    ans = [[0]*len(b[0]) for _ in range(len(a))]
    for i in range(len(a)):
        for j in range(len(b[0])):
            for k in range(len(b)):
                ans[i][j] += a[i][k]*b[k][j]%MOD
                ans[i][j] %= MOD
    return ans

N, M = map(int, input().split())
G = [[] for _ in range(N)]
for _ in range(M):
    u, v = map(int, input().split())
    u, v = u-1, v-1
    G[u].append(v)
    G[v].append(u)
S, T, A, B = map(int, input().split())

A, B = A-1, B-1

dp = [[0]*N for _ in range(N)]
for n in range(N):
    p = inverse(1, len(G[n]))
    for v in G[n]:
        dp[v][n] = p

dp = [[d[:] for d in dp]]
for _ in range(59):
    dp.append(matrix(dp[-1], dp[-1]))

ans = [[0] for _ in range(N)]
ans[0][0] = 1
for i in range(60):
    if 1<<i & (T-1):
        ans = matrix(dp[i], ans)
for i in range(N):
    if i != B:
        ans[i][0] = 0
for i in range(60):
    if 1<<i & (S-T):
        ans = matrix(dp[i], ans)

ans2 = [[0] for _ in range(N)]
ans2[0][0] = 1
for i in range(60):
    if 1<<i & (S-1):
        ans2 = matrix(dp[i], ans2)

print(inverse(ans[A][0], ans2[A][0]))