#include<bits/stdc++.h>
using namespace std;
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
vector<int> data;
int input;
for(int i = 0;i < 4;++i){
cin >> input;
data.push_back(input);
}
sort(data.begin(), data.end());
if(data[0] == data[1] && data[2] == data[3]){
cout << "yes" << endl;
}else{
cout << "no" << endl;
}
return 0;
}
