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

int main(){
	int a[4];
	for(int i = 0;i < 4;i++)scanf("%d", &a[i]);
	sort(a, a+4);
	if(a[0] == a[1] && a[2] == a[3])printf("yes\n");
	else printf("no\n");
	return 0;
}
