#include <bits/stdc++.h>

using namespace std;

bool cmp(vector<int> &A,vector<int> &B)
{
  if(A.size()!=B.size()) return A.size()>B.size();
  for(int i = A.size()-1;i>0;i--)
  {
    if(A[i] != B[i])
    return A[i]>B[i];
  }
  return true;
}

vector<int> sub(vector<int>&A,vector<int>&B)
{
  vector<int> c;
  int t = 0;
  for(int i = 0;i<A.size();i++)
  {
    t = A[i]-t;
    if(i<B.size()) t -= B[i];
    c.push_back((t+10)%10);
    if(t<0) t = 1;
    else t = 0;
  }
  while(c.size()>1&&c.back() == 0) c.pop_back();
  return c;
}
int main()
{
string a,b;
vector<int> A,B;
	cin >> a >> b;
	for(int i = a.size()-1;i>=0;i--)A.push_back(a[i]-'0');
	for(int i = b.size()-1;i>=0;i--)B.push_back(b[i]-'0');
  vector<int>arr;
  if(cmp(A,B))
  arr = sub(A,B);
  else {arr = sub(B,A);cout<<"-" ;}
  for(int i = arr.size()-1;i>=0;--i) cout<<arr[i];
  return 0;
}