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