void jian(){
int res[100001];
string a,b;
long long k = 0,r = 0,i,j;
bool flag;
cout<<"请输入被减数:";cin>>a;
cout<<"请输入减数:";cin>>b;
if(a.size()<b.size()||(a.size()==b.size()&&a<b))cout<<"-";
for(i=a.size()-1,j=b.size()-1;j>=0;i--,j--){
res[k++]=(a[i]-b[j]-r);r=0;
if(res[k-1]<0){res[k-1]+=10;r=1;}
}
while(i>=0){
res[k++]=a[i]-'0'-r;r=0;
if(res[k-1]<0){res[k-1]+= 10;r = 1;}
i--;
}
cout<<"差为:";
for(i = k - 1;i>=0;i--){
if(res[i]!=0 || flag){
cout<<res[i];
flag=true;
}
}
if(!flag)cout<<0<<endl;
}