import sys
# input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################
mod = 998244353

def mat_add(A, B):
    assert len(A)==len(B) and len(A[0]) == len(B[0])
    n = len(A)
    m = len(A[0])
    for i in range(n):
        for j in range(m):
            A[i][j] += B[i][j]
            A[i][j] %= mod
    return A


def mat_mul(A,B):
    assert len(A[0]) == len(B)
    n = len(A)
    m = len(B[0])
    p = len(A[0])
    R = [[0 for j in range(m)]for i in range(n)]
    for i in range(n):
        for j in range(m):
            for k in range(p):
                R[i][j] += A[i][k]*B[k][j] % mod
                R[i][j] %= mod
    return R

def mat_pow(A, x):
    assert len(A)==len(A[0])
    n = len(A)
    R = [[0 for j in range(n)]for i in range(n)]
    for i in range(n):
        R[i][i] = 1
    while x > 0:
        if x&1:
            R = mat_mul(R, A)
        A = mat_mul(A,A)
        x >>= 1
    return R

def mat_pri(A):
    for i in A:
        print(*i)

def solve(n, g, s, t, k):
    res = mat_pow(g, k)
    return res[s][t]

n, m = na()
g = [[0] * n for i in range(n)]
deg = [0] * n
for i in range(m):
    a, b = na()
    a -= 1
    b -= 1
    g[a][b] += 1
    g[b][a] += 1
    deg[a] += 1
    deg[b] += 1

mod = 998244353
for i in range(n):
    if deg[i] == 0:
        continue
    x = pow(deg[i], mod-2, mod)
    for j in range(n):
        g[i][j] *= x
        g[i][j] %= mod

s, t, a, b = na()
a -= 1
b -= 1

print(solve(n, g, 0, b, t - 1) * solve(n, g, b, a, s - t) * pow(solve(n, g, 0, a, s - 1), mod-2, mod) % mod)