#include <stdio.h>

//Conjunto das partes => iterativo

int A[] = {1, 1, 3, 1};

int main()
{
	int i, n, j, s=0;
	n = 4;
	for(i=0; i<n; i++) s += A[i];
	if(s % 2) { printf("no\n"); return 0; }
	for(i=0; i<(1<<n);i++) {
		int s_test = 0;
		for(k=j=0;j<n;j++) if(i&(1<<j)) s_test += A[j];
		if(s_test == s/2) { printf("yes\n"); break; }
	}
	if(i == (1<<n)) printf("no\n");
	return 0;
}