Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

var sc = bufio.NewScanner(os.Stdin)

//Sliceconvtoi ...
func Sliceconvtoi() []int {
	strs := strings.Split(sc.Text(), " ")

	var ints []int
	var x int

	for _, s := range strs {
		x, _ = strconv.Atoi(s)
		ints = append(ints, x)
	}

	return ints
}

func main() {
	for sc.Scan() {
		d := Sliceconvtoi()
		fmt.Println(d[0] - d[1] - d[2] + d[3])
	}
}

C++: #include <bits/stdc++.h>
using namespace std;
using namespace std::chrono;
using ll=long long;
using ull=unsigned long long;
using uint=unsigned int;
using pii=pair<int,int>;
using pll=pair<ll,ll>;
using pdd=pair<double,double>;
const ll LINF=0x3fffffffffffffff;
const ll MOD=1000000007;
const ll MODD=0x3b800001;
const int INF=0x3fffffff;
const double DINF=numeric_limits<double>::infinity();
const vector<pii> four={{-1,0},{0,1},{1,0},{0,-1}};
#define _overload4(_1,_2,_3,_4,name,...) name
#define _overload3(_1,_2,_3,name,...) name
#define _rep1(n) _rep2(i,n)
#define _rep2(i,n) _rep3(i,0,n)
#define _rep3(i,a,b) for(ll i=a;i<b;++i)
#define _rep4(i,a,b,c) for(ll i=a;i<b;i+=c)
#define rep(...) _overload4(__VA_ARGS__,_rep4,_rep3,_rep2,_rep1)(__VA_ARGS__)
#define _rrep1(n) _rrep2(i,n)
#define _rrep2(i,n) _rrep3(i,0,n)
#define _rrep3(i,a,b) for(ll i=b-1;i>=a;i--)
#define _rrep4(i,a,b,c) for(ll i=a+(b-a-1)/c*c;i>=a;i-=c)
#define rrep(...) _overload4(__VA_ARGS__,_rrep4,_rrep3,_rrep2,_rrep1)(__VA_ARGS__)
#define each(i,a) for(auto&& i:a)
#define sum(...) accumulate(range(__VA_ARGS__),0LL)
#define dsum(...) accumulate(range(__VA_ARGS__),double(0))
#define _range(i) (i).begin(),(i).end()
#define _range2(i,k) (i).begin(),(i).begin()+k
#define _range3(i,a,b) (i).begin()+a,(i).begin()+b
#define range(...) _overload3(__VA_ARGS__,_range3,_range2,_range)(__VA_ARGS__)
#define yes(i) out(i?"yes":"no")
#define Yes(i) out(i?"Yes":"No")
#define YES(i) out(i?"YES":"NO")
#define Possible(i) out(i?"Possible":"Impossible")
#define elif else if
#define unless(a) if(!(a))
#define mp make_pair
#define INT(...) int __VA_ARGS__;in(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;in(__VA_ARGS__)
#define STR(...) string __VA_ARGS__;in(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__;in(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__;in(__VA_ARGS__)
#define vec(type,name,...) vector<type> name(__VA_ARGS__)
#define VEC(type,name,size) vector<type> name(size);in(name)
#define vv(type,name,h,...) vector<vector<type>>name(h,vector<type>(__VA_ARGS__))
#define VV(type,name,h,...) vector<vector<type>>name(h,vector<type>(__VA_ARGS__));in(name)
__attribute__((constructor)) void SETTINGS(){cin.tie(0); cout.tie(0); ios::sync_with_stdio(0); cout<<fixed<<setprecision(15);};
template<class T>
inline constexpr T gcd (T a,T b) {if(!a||!b)return 0;return a%b?gcd(b,a%b):b;}
template<class T>
inline constexpr T lcm (T a,T b) {a*b/gcd(a,b);}
template<class T>
inline constexpr T min(vector<T>& v){return *min_element(range(v));}
inline char min(string& v){return *min_element(range(v));}
template<class T>
inline constexpr T max(vector<T>& v){return *max_element(range(v));}
inline char max(string& v){return *max_element(range(v));}
inline ll pow(ll a,ll b){if(b==0)return 1;ll ans=pow(a,b/2);return ans*ans*(b&1?a:1);}
template<typename T>
inline bool update_min(T& mn,const T& cnt){if(mn>cnt){mn=cnt;return 1;}else return 0;}
template<typename T>
inline bool update_max(T& mx,const T& cnt){if(mx<cnt){mx=cnt;return 1;}else return 0;}
inline void in() {}
template<class T>
istream& operator >> (istream& is, vector<T>& vec);
template<class T,size_t size>
istream& operator >> (istream& is, array<T,size>& vec);
template<class T,class L>
istream& operator >> (istream& is, pair<T,L>& p);
template<class T>
ostream& operator << (ostream& os, vector<T>& vec);
template<class T,class L>
ostream& operator << (ostream& os, pair<T,L>& p);
template<class T>
istream& operator >> (istream& is, vector<T>& vec){for(T& x: vec) is >> x;return is;}
template<class T,class L>
istream& operator >> (istream& is, pair<T,L>& p){is >> p.first;is >> p.second;return is;}
template<class T>
ostream& operator << (ostream& os, vector<T>& vec){os << vec[0];rep(i,1,vec.size()){os << ' ' << vec[i];}return os;}
template<class T>
ostream& operator << (ostream& os, deque<T>& deq){os << deq[0];rep(i,1,deq.size()){os << ' ' << deq[i];}return os;}
template<class T,class L>
ostream& operator << (ostream& os, pair<T,L>& p){os << p.first << " " << p.second;return os;}
template<class T,class L>
pair<T,L> operator + (pair<T,L> a, pair<T,L> b){return {a.first + b.first, a.second + b.second};}
template <class Head, class... Tail>
inline void in(Head&& head,Tail&&... tail){cin>>head;in(move(tail)...);}
template <class T>
inline bool out(T t){cout<<t<<'\n';return 0;}
inline bool out(){cout<<'\n';return 0;}
template <class Head, class... Tail>
inline bool out(Head head,Tail... tail){cout<<head<<' ';out(move(tail)...);return 0;}
template <class T>
inline void err(T t){cerr<<t<<'\n';}
inline void err(){cerr<<'\n';}
template <class Head, class... Tail>
inline void err(Head head,Tail... tail){cerr<<head<<' ';out(move(tail)...);}



signed main(){
    INT(n,a,b,c);
    out(a+b-c);
}

C++: #include <string>
#include <iostream>
#include <math.h>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <map>
#include <set>
typedef long long ll;
const int mod=1e9+7;
#define lol(i,n) for(int i=0;i<n;i++)

using namespace std;
int n,a,b,c;
int main() {
    cin >>n>>a>>b>>c;
    int k=a+b-c;
    cout << n-k<< endl;
}

C++: #include<iostream>
#include<vector>
#include<string>
#include<algorithm>
using namespace std;
long long rui(long long n, long long k, long long p) {
	if (k == 0) {
		return 1;
	}
	else {
		long long a = rui(n, k / 2, p);
		if (k % 2 == 0) {
			return (a*a) % p;
		}
		return (((a*a) % p)*n) % p;
	}
}
int main(){
	int n, a, b, c;
	cin >> n >> a >> b >> c;
	cout << n - a - b + c << endl;
}

C++: /*  -*- coding: utf-8 -*-
 *
 * 2919.cc: Training
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

/* global variables */

/* subroutines */

/* main */

int main() {
  int n, a, b, c;
  scanf("%d%d%d%d", &n, &a, &b, &c);

  printf("%d\n", n - (a + b - c));
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
int main() {
	long N, A, B, C; cin >> N >> A >> B >> C;
	cout << N - (A + B - C) << endl;
}

C++: #include <bits/stdc++.h>
using i64 = long long;
using std::cout;
using std::endl;
using std::cin;

int main() {
	int n, a, b, c; scanf("%d%d%d%d", &n, &a, &b, &c);
	
	printf("%d\n", n - (a + b - c));
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; i++)

int main() {
	int n, a, b, c;
	cin >> n >> a >> b >> c;
	cout << n - a - b + c << endl;
}

C++: //include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <climits>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
#include <random>
#include <complex>
#include <regex>

using namespace std;

#define SHOW_VECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOW_MAP(v){std::cerr << #v << endl; for(const auto& xxx: v){std::cerr << xxx.first << " " << xxx.second << "\n";}}


int main() {

    int N, A, B, C;
    cin >> N >> A >> B >> C;

    cout << N - (A + B - C) << endl;

}