include<bits/stdc++.h>

using namespace std; int a[250],b[250],c[250]; int main() {

string sa,sb;
cin>>sa>>sb;
int  lena=sa.size();
int  lenb=sb.size();
if(lena<lenb||lena==lenb&&sa<sb) 
{
	cout<<"-";
	swap(sa,sb);
	swap(lena,lenb);
}
for(int i=0;i<lena;i++)
{
	a[i]=sa[lena-1-i]-'0';
}
for(int i=0;i<lenb;i++)
{
	b[i]=sb[lenb-1-i]-'0';
}
int lenc=max(lena,lenb);
for (int i=0;i<lenc;i++)
{
	if (a[i]<b[i])
	{
		a[i+1]--;
		a[i]+=10;
	}
	c[i]=a[i]-b[i];
}
while(c[lenc]==0&&lenc!=0)
{
	lenc--;
}
for (int i=lenc;i>=0;i--)
{
	cout<<c[i];
}
return 0;

}