#include<iostream>
#include<cstring>
using namespace std;
int main()
{
    int a[100005],i,fu=0,s,n1,n2,k,max,min;
    memset(a,0,sizeof(a));
    string m1,m2;
    cin>>m1>>m2;
    n1=m1.size();
    n2=m2.size();
    for(i=n1-1;i>=0;i--)a[n1-i-1]=m1[i]-'0';
    for(i=n2-1;i>=0;i--){
        s=a[n2-i-1]-(m2[i]-'0');
        if(s>=0)a[n2-i-1]=s;
        else{
            if(n2-i>n1-1){
                fu=1;
                break;
            }
            a[n2-i-1]=s+10;
            a[n2-i]--;
        }    
    }
    max=n1,min=n2;
    if(fu){
        for(i=n2-1;i>=0;i--)a[n2-i-1]=m2[i]-'0';
        for(i=n1-1;i>=0;i--){
            s=a[n1-i-1]-(m1[i]-'0');
            if(s>=0)a[n1-i-1]=s;
            else{
                a[n1-i-1]=s+10;
                a[n1-i]--;          
            }    
        }
        max=n2,min=n1;
        cout<<'-';
    }
    for(i=min;i<=max-1;i++){
        if(a[i]<0){
            a[i]+=10;
            a[i+1]--;
        }
    }
    k=0;
    for(i=max;i>=0;i--){
        if(a[i]>0){
            k=i;
            break;
        }
    }
    for(i=k;i>=0;i--)printf("%d",a[i]);
    printf("\n");
    return 0;
}