#include<bits/stdc++.h>
using namespace std;

 int main(){

  int a,b,c,d;
  cin>>a>>b>>c>>d;

  if((a==b && c==d) || (a==c &&b==d) || (a==d &&c==b)  )    cout<<"yes"<<endl;
  else cout<<"no"<<endl;

  return 0;
  }

