#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(void){
vector<int> v;
int t;
for (int i=0; i<4; i++){
cin>>t;
v.push_back(t);
}
sort(v.begin(), v.end());
cout << (v[0]==v[1]&&v[2]==v[3]?"yes":"no") << endl;
return 0;
}
