#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <iomanip>
#include <set>
using namespace std;
#define rep(i,n) for((i)=0;(i)<(n);(i)++)
#define setpre(n) fixed << setprecision(n)
template<class T,class C> T max(T a,C b){ return std::max(a, (T)b); }
template<class T,class C> T min(T a,C b){ return std::min(a, (T)b); }
template<class T,class C> bool chmax(T &a,const C b){ if(a<(T)b){ a=(T)b;return true; } return false; }
template<class T,class C> bool chmin(T &a,const C b){ if((T)b<a){ a=(T)b;return true; } return false; }
using ll = long long;
using ld = long double;
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
#define YES(b) (b?"YES":"NO")
#define Yes(b) (b?"Yes":"No")
#define yes(b) (b?"yes":"no")
int main(){
  ll n,m,i,j,k,result=0;
  string s;
  
  cin >> s;
  set<char> ss;
  n = s.size();
  
  cout << Yes(n==2) << endl;
  return 0;
}