#include<bits/stdc++.h>
#include<vector>
#include<string>
#include<algorithm>
#include<cmath>

#define fast ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define int long long int
#define mod 1000000007
#define inf 1e18+42
#define endl "\n"
#define pi 3.1415926535897932384626433832795028841971693993751058
#define maxn 100005

#define out1(a) cout<<#a<<" "<<a<<endl
#define out2(a,b) cout<<#a<<" "<<a<<" "<<#b<<" "<<b<<endl
#define out3(a,b,c) cout<<#a<<" "<<a<<" "<<#b<<" "<<b<<" "<<#c<<" "<<c<<endl

#define rep(i,a,b) for(int i=a;i<b;i++)
#define repr(i,a,b) for(int i=a;i>=b;i--)
#define fori(it,A) for(auto it=A.begin();it!=A.end();it++)

#define ft first
#define sd second
#define pb push_back
#define mp make_pair
#define pq priority_queue
#define all(x) (x).begin(),(x).end()
#define zero(x) memset(x,0,sizeof(x));
#define ceil(a,b) (a+b-1)/b
 
using namespace std;

int binpow(int a, int b) {
    int res = 1;
    while (b > 0) {
        if (b & 1)
            res = res * a;
        a = a * a;
        b >>= 1;
    }
    return res;
}

//START OF CODE ->->->->->->->

void solve()
{
    int a,b,c,d;
    cin>>a>>b;
    cin>>c>>d;
    cout<<b-c<<endl;
}

//END OF CODE ->->->->->->->->

signed main()
{
    fast;
    int t = 1;
    // cin>>t;

    while(t--)
    {
        solve();
    }
    return 0;
}


// Problem: A - Difference Max
// Contest: AtCoder - AtCoder Beginner Contest 196
// URL: https://atcoder.jp/contests/abc196/tasks/abc196_a
// Memory Limit: 1024 MB
// Time Limit: 2000 ms
// Parsed on: 20-03-2021 17:30:12 IST (UTC+05:30)
// Author: Kapil Choudhary
// ********************************************************************
// कर्मण्येवाधिकारस्ते मा फलेषु कदाचन |
// मा कर्मफलहेतुर्भूर्मा ते सङ्गोऽस्त्वकर्मणि || १.४७ ||
// ********************************************************************

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

#define ll long long
#define ull unsigned long long
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define PI 3.1415926535897932384626
#define deb(x) cout << #x << "=" << x << endl
#define deb2(x, y) cout << #x << "=" << x << ", " << #y << "=" << y << endl
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int>	vi;
typedef vector<ll> vll;
typedef vector<ull> vull;
typedef vector<pii>	vpii;
typedef vector<pll>	vpll;
typedef vector<vi> vvi;
typedef vector<vll>	vvll;
typedef vector<vull> vvull;
mt19937_64 rang(chrono::high_resolution_clock::now().time_since_epoch().count());
int rng(int lim) {
    uniform_int_distribution<int> uid(0,lim-1);
    return uid(rang);
}

const int INF = 0x3f3f3f3f;
const int mod = 1e9+7;

void solve()
{
  	int a, b, c, d;
  	cin >> a >> b >> c >> d;
  	
  	int x = b, y = c;
  	cout << x - y << "\n";
}

int main()
{
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    srand(chrono::high_resolution_clock::now().time_since_epoch().count());

    // #ifndef ONLINE_JUDGE
    //     freopen("input.txt", "r", stdin);
    //     freopen("output.txt", "w", stdout);
    // #endif

    int t = 1;
    // cin >> t;
    while(t--) {
      solve();
    }

    return 0;
}