#include<bits/stdc++.h>
using namespace std;
int a[10086],b[10086],c[10086],lena,lenb,lenc,i;
int main(){
    char n[10086],n1[10086],n2[10086];
    cin>>n1;
    cin>>n2;
    if(strlen(n1)<=strlen(n2)&&strcmp(n1,n2)<0){
        strcpy(n,n1);
        strcpy(n1,n2);
        strcpy(n2,n);
        cout<<"-";
    }
    lena=strlen(n1);
    lenb=strlen(n2);
    for(i=0;i<lena-1;i++)
        a[lena-i]=int(n1[i]-'0');
    for(i=0;i<lenb-1;i++)
        b[lenb-i]=int(n2[i]-'0');
    i=1;
    while(i<=lena||i<=lenb){
        if(a[i]<b[i]){
            a[i+1]--;
            a[i]+=10;
        }
        c[i]=a[i]-b[i];
        i++;
    }
    lenc=i;
    while(c[lenc]=0&&lenc>1)
        lenc--;
    for(i=lenc;i>=1;i--)
        cout<<c[i];
    cout<<endl;
    return 0;
}