You are given a string $s$, consisting of $n$ lowercase Latin letters.

A substring of string $s$ is a continuous segment of letters from $s$. For example, "defor" is a substring of "codeforces" and "fors" is not. 

The length of the substring is the number of letters in it.

Let's call some string of length $n$ diverse if and only if there is no letter to appear strictly more than $\frac n 2$ times. For example, strings "abc" and "iltlml" are diverse and strings "aab" and "zz" are not.

Your task is to find any diverse substring of string $s$ or report that there is none. Note that it is not required to maximize or minimize the length of the resulting substring.


-----Input-----

The first line contains a single integer $n$ ($1 \le n \le 1000$) — the length of string $s$.

The second line is the string $s$, consisting of exactly $n$ lowercase Latin letters.


-----Output-----

Print "NO" if there is no diverse substring in the string $s$.

Otherwise the first line should contain "YES". The second line should contain any diverse substring of string $s$.


-----Examples-----
Input
10
codeforces

Output
YES
code

Input
5
aaaaa

Output
NO



-----Note-----

The first example has lots of correct answers. 

Please, restrain yourself from asking if some specific answer is correct for some specific test or not, these questions always lead to "No comments" answer.

Difficulty: interview

Starter code:

Solutions:
n = int(input())
s = input()
for i in range(n - 1):
    if (s[i] != s[i+1]):
        print("YES")
        print(s[i:i+2])
        return
print("NO")


n = int(input())
s = input()
for i in range(n - 1):
    if s[i] != s[i + 1]:
        print("YES")
        print(s[i] + s[i+1])
        break
else:
    print("NO")

input()
s = input()
for i in range(len(s) - 1):
    if s[i] != s[i + 1]:
        print("YES")
        print(s[i:i + 2])
        return
print("NO")


n=int(input())
s=input()
if(n==1):
    print("NO")
else:
    for x in range(n-1):
        a,b=s[x],s[x+1]
        if(a!=b):
            print("YES")
            print(a+b)
            break
    else:
        print("NO")

n = int(input())
s = input()

for i in range(n-1):
    if s[i] != s[i+1]:
        print('YES')
        print(s[i:i+2])
        return

print('NO')

read = lambda: [int(i) for i in input().split()]

n = read()[0]
s = input()
for i in range(n - 1):
    if s[i] != s[i + 1]:
        print('YES\n' + s[i] + s[i + 1])
        return
print('NO')

n = int(input())
a = input()
for i in range(n - 1):
    if a[i] != a[i + 1]:
        print("YES")
        print(a[i] + a[i + 1])
        return
print("NO")

n = int(input())
s = input()
for i in range(len(s) - 1):
    if(s[i] != s[i + 1]):
        print("YES")
        print(s[i] + s[i + 1])
        break
else:
    print("NO")

def ii():
    return int(input())
def mi():
    return list(map(int, input().split()))
def li():
    return list(mi())

n = ii()
s = input().strip()
ans = 'NO'
for i in range(n - 1):
    if s[i] != s[i + 1]:
        ans = 'YES\n' + s[i:i + 2]
        break
print(ans)


n = int(input())
# a = list(map(int,input().split()))
# m = int(input())
s = input()
f = s[0]
for c in s:
    if c != f:
        print('YES')
        print(f + c)
        return
print('NO')

n=int(input())
r=input()
l=len(r)
for i in range(l-1):
	if (r[i]!=r[i+1]):
		print ("YES")
		print (r[i]+r[i+1])
		return
print ("NO")

b=int(input())
a=input()
done=0
for i in range(len(a)-1):
    if not a[i]==a[i+1]:
        print("YES")
        print(a[i]+a[i+1])
        done=1
        break
if done==0:
    print("NO")

def go():
    n = int(input())
    a = [i for i in input()]
    if n == 1:
        print('NO')
        return
    for i in range(n - 1):
        if a[i] != a[i + 1]:
            print('YES')
            print(a[i] + a[i + 1])
            return
    if a[len(a) - 1] != a[len(a) - 2]:
        print('YES')
        print(a[len(a) - 1] + a[len(a) - 2])
        return

    print('NO')

go()


n = int(input())
s = input()
if len(set(list(s))) == 1:
    print("NO")
else:
    print("YES")
    for i in range(n - 1):
        if s[i] != s[i + 1]:
            print(s[i] + s[i + 1])
            break


n = int(input())
s = input()
if len(set(list(s))) == 1:
    print("NO")
    return
for i in range(1, n):
    if s[i] != s[i-1]:
        print("YES")
        print(s[i-1]+s[i])
        return

n= int(input())
s = input()
ans = 0
for i in range(n-1):
	if s[i] != s[i+1]:
		ans = 1
		ans1 = i
		break
if ans == 1:
	print("YES")
	print(s[i]+s[i+1])
else:
	print("NO")

input()
s = input()
for i in range(len(s)-1):
    if s[i] != s[i+1]:
        print('YES')
        print(s[i]+s[i+1])
        break
else:
    print('NO')


n = int(input())
s = input()

flag = False

for i in range(len(s) - 1):
    if flag:
        break
    if s[i] != s[i + 1]:
        print("YES")
        print(s[i:i+2])
        flag = True
if not flag:
    print("NO")

n = int(input())
s = input()
for i in range(1, n):
    if s[i] != s[i-1]:
        print("YES")
        print(s[i-1]+s[i])
        break
else:
    print("NO")


n = int(input())
s = input()

found = False
res = ""

for i in range(n-1):
	if s[i] != s[i+1]:
		found = True
		res = s[i] + s[i+1]
		break

if found:
	print("YES")
	print(res)
else:
	print("NO")

import sys

n=int(input())
s=input()

for i in range(1,n):
    if s[i]!=s[i-1]:
        print("YES")
        print(s[i-1]+s[i])
        return

print("NO")


def main():
    _ = input()
    n = input()
    for i in range(len(n) - 1):
        if n[i] != n[i + 1]:
            print("YES")
            print(n[i:i + 2])
            return
    print("NO")


main()

import math, sys

def mp():
    return list(map(int, input().split()))

def main():
    n = int(input())
    a = input().strip()
    for i in range(n - 1):
        if a[i] != a[i + 1]:
            print('YES') 
            print(a[i] + a[i + 1])
            return
    print("NO")
            
    
    

deb = 0
if deb:
    file = open("input.txt", "r")
    input = file.readline
else:
    input = sys.stdin.readline

main()

if deb:
    file.close()