q="ss"
zf=[]
l=input()
s,e=map(str,l.split())
while True:
    q=input().strip()
    if q=="":break
    if q!="":
        a=q.split()
        zf.append(a)
head,tail=0,1
g=[[],[s,0]]
k=[]
u=False
st=0
while head<tail:
    if st>=10:
        print("NO ANSWER!")
        break
    head+=1
    st=g[head][1]+1
    for i in range(len(zf)):
        if zf[i][0] in g[head][0]:
            nz=g[head][0].replace(zf[i][0],zf[i][1])
            if nz not in k:
                tail+=1
                g.append([nz,st])
                k.append(nz)
                if nz==e:
                    print(st)
                    u=True
                    break
    if u:break

是输入的问题么