#include<bits/stdc++.h> using namespace std; int a[5005],b[5005],c[5005]; int main(){ string a1,b1; cin>>a1>>b1; if(a1.size()<b1.size()||(a1<b1)){ swap(a1,b1); cout<<"-"; } int la=a1.size(); int lb=b1.size(); for(int i=1;i<=la;i++) a[i]=a1[la-i]-'0'; for(int i=1;i<=lb;i++) b[i]=b1[lb-i]-'0'; int lc=la+1; for(int i=1;i<=lc;i++){ if(a[i]<b[i]){ a[i]+=10; a[i+1]--; } c[i]=a[i]-b[i]; } while(c[lc]==0&&lc!=0) lc--; for(int i=lc;i>=1;i--){ cout<<c[i]; } }