#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<queue>
#include<map>
#include<math.h>
#include<iomanip>
#include<set>
#include<numeric>
#include<cstring>
#include<cstdio>
#include<functional>
#include<bitset>
#include<limits.h>
#include<cassert>
#include<iterator>
#include<complex>
#include<stack>
#include<sstream>
using namespace std;
typedef  long long int lint;
typedef pair<int, int> IP;
typedef pair<lint, lint> LLP;
typedef pair<char, char>CP;
#define rep(i, n) for (int i = 0; i < n; i++)
#define repr(i, n) for (int i = n; i >= 0; i--)
#define sort(v) sort((v).begin(), (v).end())
#define reverse(v) reverse((v).begin(), (v).end())
#define upper(v,hoge) upper_bound(v.begin(),v.end(),hoge)
#define lower(v,hoge) lower_bound(v.begin(),v.end(),hoge)
#define llower(v,hoge) *lower_bound(v.begin(), v.end(), hoge)
#define lupper(v,hoge) *upper_bound(v.begin(), v.end(), hoge)
#define toupper(S) transform(S.begin(),S.end(),S.begin(),toupper)
#define tolower(S) transform(S.begin(),S.end(),S.begin(),tolower)
//const lint MOD = pow(10, 9) + 7;

int main() {
	vector<int>A(4);
	rep(i, 4) {
		cin >> A[i];
	}
	sort(A);
	if (A[0] + 1 == A[1] && A[0] + 2 == A[2] & A[0] + 3 == A[3]) {
		cout << "Yes" << endl;
	}
	else {
		cout << "No" << endl;
	}
}