#include <iostream>
#include <bits/stdc++.h>
using namespace std;
int main(void){
int number[4];
for(int i = 0; i < 4; i++){
cin >> number[i];
}
sort(number, number + 4);
if((number[0] == number[1]) && (number[2] == number[3])){
cout << "yes" << endl;
}else{
cout << "no" << endl;
}
return 0;
}