#include <iostream>

#include <algorithm>
using namespace std;

int main() {
   
   string answer;
 int l, i=0, a[100];
    while(cin>>l){
        a[i] = l;
       
        i++;
    }
  sort(a, a+l);
     answer = "Yes";
     
        for (int i = 0; i < 3; ++i) 
    {      

            if (a[i]+1 != a[i+1]){ answer = "No"; break;}
    }        
     cout <<answer<< endl;
     return 0;
        }