#include<bits/stdc++.h>
using namespace std;
int x,y,a;
string s;
int main()
{
	cin>>s;
	a=s.size();
	x=0;y=a-1;
	while(s[x]==s[y]&&x<y)
	{
		x++;
		y--;
	}
	if(x==y) cout<<"js";
		else if(x>y) cout<<"os";
			else cout<<"NO";
	return 0;
}