#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define FASTIO ios_base::sync_with_stdio(false); cin.tie(NULL);

int main () {
    FASTIO
    int n, m;
    cin>>n>>m;
    ll s = 0;
    for (ll i = 1; i < 1000000000; i++) {
        s += i;
    }
    cout<<n - m;
    return 0;
}