#include <bits/stdc++.h>
using namespace std;

int main()
{
	char a1[10000],b1[10000],n[20100];
	int a[20000],b[20000],c[20000];
	int lena,lenb,lenc,i;
	memset(a,0,sizeof(a));
	memset(b,0,sizeof(b));
	memset(c,0,sizeof(c));
	
	cin >> a1 >> b1;
	lena = strlen(a1);
	lenb = strlen(b1);
	for(i=0;i<=lena-1;i++)
		a[lena - i] = int(a1[i] - '0');
	for(i=0;i<=lenb-1;i++)
		b[lenb - i] = int(b1[i] - '0');
	for(i=1;i<=lena;i++)
	{
		if(a[i] < b[i])
		{
			a[i] += 10;
			a[i+1]--;
		}
		c[i] = a[i]-b[i];  
	}
	lenc = i;
	while(c[lenc] == 0 && lenc > 1)
		lenc--;
	for(i=lenc;i>=1;i--)
		cout << c[i];
			
	return 0; 
}

P2142 高精度减法