cf 1230A

#include<bits/stdc++.h>

using namespace std;

int main()
{
    int a[4], i;
    for(i = 0; i < 4; i++) scanf("%d", &a[i]);

    sort(a, a+4);

    if((a[0] + a[3] == a[1] + a[2]) || (a[0] + a[1] + a[2] == a[3])) printf("YES\n");
    else printf("NO\n");
}