#include<bits/stdc++.h>
using namespace std;
int main()
{
	string s1,s2;
	int a[10100]={0},b[10100]={0},c[10100]={0},a1,a2;
	cin>>s1>>s2;
	a1=s1.length();
	a2=s2.length();
	if(a1<a2||(a1==a2&&s1<s2))
	{
		cout<<"-";
		swap(a1,a2);
		swap(s1,s2);
		
	}
	for(int i=0;i<a1;i++)
		a[a1-i]=s1[i]-'0';
	for(int i=0;i<a2;i++)
		b[a2-i]=s2[i]-'0';
	for(int i=0;i<=a1;i++)
	{
		if(a[i]<b[i])
			a[i]+=10,a[i+1]--;
		c[i]=a[i]-b[i];
	}
	while(a1!=1&&c[a1]==0)
		a1--;
	for(int i=k;i>=0;i--)
		cout<<c[i];
	return 0;
}