#include<iostream>

#include<cstdio>

#include<cstdlib>

#include<cstring>

#include<string>

#include<algorithm>

#include<cmath>

#include<iomanip>

int a[],b[],c[],lena,lenb,lenc,i;

char n[],n1[],n2[];

using namespace std;

int main()

{

    scanf("%s",n1);

    scanf("%s",n2);

    if(strlen(n1)<strlen(n2)||(strlen(n1)==strlen(n2)&&strcmp(n1,n2)<))

    {

        strcpy(n,n1);

        strcpy(n1,n2);

        strcpy(n2,n);

        cout<<"-";

    }

    lena=strlen(n1);lenb=strlen(n2);

    for(i=;i<=lena-;i++) a[lena-i]=int(n1[i]-'');

    for(i=;i<=lenb-;i++) b[lenb-i]=int(n2[i]-'');

    i=;

    while(i<=lena||i<=lenb)

    {

        if(a[i]<b[i])

        {

            a[i]+=;

            a[i+]--;

        }

        c[i]=a[i]-b[i];

        i++;

    }

    lenc=i;

    while((c[lenc]==)&&(lenc>)) lenc--;

    for(i=lenc;i>=;i--) cout<<c[i];

    return ;

}

a=input()

b=input()

print int(a)-int(b)