#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int main(){
	int a[100010],b[100010],c[100010],la,lb,lc,i;
	char n[100010],n1[100010],n2[100010];
	cin>>n1;
	cin>>n2;
	if (strlen(n1)<strlen(n2)||(strlen(n1)==strlen(n2)&&strcmp(n1,n2)<0)){
		strcpy(n,n1);
		strcpy(n1,n2);
		strcpy(n2,n);
		cout<<"-";
	}
	la=strlen(n1); lb=strlen(n2);
	for(i=0;i<la-1;i++)a[la-i]=int(n1[i]-'0');
	for(i=0;i<lb-1;i++)b[lb-i]=int(n2[i]-'0');
	i=0;
	while (i<=la||i<=lb){
		if (a[i]<b[i]){
			a[i]+=10;
			a[i+1]--;
		}
		c[i]=a[i]-b[i];
		i++;
	}
	lc=i;
	while ((c[lc]==0)&&(lc>1)) lc--;
	for (i=lc;i>=1;i--) cout<<a[i];
	cout<<endl;
	return 0;
} 

求各位大佬修改代码