#include <stdio.h>
#include <stdlib.h>

int comp(const void* x, const void* y)
{
    return *(int*)x - *(int*)y;
}

int main(int argc, char const* argv[])
{
    int n[4];
    scanf("%d %d %d %d", &n[0], &n[1], &n[2], &n[3]);
    qsort(n, 4, sizeof(int), comp);
    if (n[0] + 1 != n[1] || n[0] + 2 != n[2] || n[0] + 3 != n[3])
        printf("No");
    else
        printf("Yes");
}