自己用海龟测试无问题 一上洛谷就RE

flag=0
ans=[]
s=input()
d=input()
an=""
p=s
q=d
if(len(s)>len(d)):
    flag=1
    for x in range(len(s)-len(d)):
        d="0"+d
if(len(s)<len(d)):
    flag=2
    for x in range(len(d)-len(s)):
        s="0"+s
if(s==d):
    print(0)
else:
    if(((flag==0)and(s>d))or(len(p)>len(q))):
        wei=0
        for x in range(len(s)):
            i=len(s)-1-x
            if((int(s[i])-wei)>=int(d[i])):
                ans.append(int(s[i])-wei-int(d[i]))
                wei=0
            else:
                ans.append(int(s[i])-wei+10-int(d[i]))
                wei=1
        an=""
        for x in range(len(ans)):
            if(ans[len(ans)-1-x]!=0):
                break
            else:
                ans[len(ans)-1-x]=-2
        for x in range(len(ans)):
            if(ans[len(ans)-1-x]>=0):
                an=an+str(ans[len(ans)-1-x])
        print(an)
    if(((flag==0)and(s<d))or(len(p)<len(q))):
        wei=0
        for x in range(len(s)):
            i=len(s)-1-x
            if((int(d[i])-wei)>=int(s[i])):
                ans.append(int(d[i])-wei-int(s[i]))
                wei=0
            else:
                ans.append(int(d[i])-wei+10-int(s[i]))
                wei=1
        an="-"
        for x in range(len(ans)):
            if(ans[len(ans)-1-x]!=0):
                break
            else:
                ans[len(ans)-1-x]=-2
        for x in range(len(ans)):
            if(ans[len(ans)-1-x]>=0):
                an=an+str(ans[len(ans)-1-x])
        print(an)