#include<iostream>
#include<algorithm>
#include<stack>
#include<queue>
using namespace std;
int main(){
	int e[4];
	for(int i=0;i<4;i++){
		cin>>e[i];
	}
	sort(e,e+4);
	if(e[0]==e[1] && e[2]==e[3]){
		cout<<"yes"<<endl;
	}
	else {
		cout<<"no"<<endl;
	}
	return 0;
}