n=int(input().split(" ")[0])
dls=input().split(" ")
bls=list()
for i in range(0,n):
bls.append(int(dls[i]))
for i in bls:
for j in bls:
for k in bls:
y=sorted([i,j,k])
if y[1]-y[0]==y[2]-y[1]==1:
print("YES")
exit(0)
print("NO")
#include <iostream>
#include <algorithm>
#include <cstdlib>
using namespace std;
int t[51],fr[1001];
int main()
{
int n,ok;
cin>>n;
for(int i=1; i<=n; ++i){
cin>>t[i];
fr[t[i]]++;}
ok=0;
for(int i=1; i<=1000; ++i){
if((fr[i] != 0) && (fr[i+1] != 0) && (fr[i+2] != 0))
ok=1;}
if(ok == 1)
cout<<"YES";
else
cout<<"NO";
return 0;
}
1005B - Delete from the Left | 94A - Restoring Password |
1529B - Sifid and Strange Subsequences | 1455C - Ping-pong |
1644C - Increase Subarray Sums | 1433A - Boring Apartments |
1428B - Belted Rooms | 519B - A and B and Compilation Errors |
1152B - Neko Performs Cat Furrier Transform | 1411A - In-game Chat |
119A - Epic Game | 703A - Mishka and Game |
1504C - Balance the Bits | 988A - Diverse Team |
1312B - Bogosort | 1616B - Mirror in the String |
1660C - Get an Even String | 489B - BerSU Ball |
977C - Less or Equal | 1505C - Fibonacci Words |
1660A - Vasya and Coins | 1660E - Matrix and Shifts |
1293B - JOE is on TV | 1584A - Mathematical Addition |
1660B - Vlad and Candies | 1472C - Long Jumps |
1293D - Aroma's Search | 918A - Eleven |
1237A - Balanced Rating Changes | 1616A - Integer Diversity |