#include <iostream>
using namespace std;
int main(void){
    int a,b,c,d;
    cin >> a >> b >> c >> d;
    
    if(a == b && c == d){
        cout << "yes" << endl;
    }
    else if(a == c && b == d){
        cout << "yes" << endl;
    }
    else if(a == d && b == c){
        cout << "yes" << endl;
    }
    else{
        cout << "no" << endl;
    }
}
