MOD = 998244353

# 条件付確率わからん！ぐぐりました(敗北)

def matmul(A, B):
    N = len(A)
    C = [[0] * N for _ in range(N)]
    for k in range(N):
        for i in range(N):
            for j in range(N):
                C[i][j] += A[i][k] * B[k][j]
                C[i][j] %= MOD
    return C
 
def matpow(M, K):
    N = len(M)
    res = [[0] * N for _ in range(N)]
    for i in range(N): res[i][i] = 1
    mul = M
    while K:
        if K & 1:
            res = matmul(res, mul)
        mul = matmul(mul, mul)
        K >>= 1
    return res

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)

mat = [[0] * N for _ in range(N)]
for i in range(N):
    deg = len(G[i])
    for j in G[i]:
        mat[i][j] += pow(deg, -1, MOD)

S, T, A, B = map(int, input().split())
A, B = A - 1, B - 1
P_B = matpow(mat, S - 1)[0][A]
P_A = matpow(mat, T - 1)[0][B] * matpow(mat, S - T)[B][A]
P_A %= MOD
print((P_A * pow(P_B, -1, MOD)) % MOD)