def m(S,T):L=len(S);return[[sum(s[j]*T[j][k]for j in R(L))%P for k in R(L)]for s in S]
def p(T,n):
	L=len(T);a=[[i==j for j in R(L)]for i in R(L)]
	while n:
		if n&1:a=m(a,T)
		T=m(T,T);n>>=1
	return a
R=range
J=lambda:map(int,input().split())
N,M=J()
E=[[]for i in R(N)]
for j in R(M):u,v=J();E[u-1]+=[v-1];E[v-1]+=[u-1]
C=[[0]*N for i in R(N)]
P=998244353
for i in R(N):
	r=pow(len(E[i]),-1,P)
	for j in E[i]:C[i][j]=r
S,T,A,B=J()
v=p(C,T-1)[0]
C=p(C,S-T)
print(v[B-1]*C[B-1][A-1]*pow(sum(v[i]*C[i][A-1]for i in R(N)),-1,P)%P)