#include <iostream>
#include <vector>
#include <algorithm>
#include <deque>
#include <queue>
#include <string>
#include <iomanip>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <utility>
#include <stack>
#include <random>
#include <complex>
#include <functional>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <assert.h>
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
#endif
using namespace std;
using ll=long long;
#define read(x) cin>>(x);
#define readll(x) ll (x);cin>>(x);
#define readS(x) string (x);cin>>(x);
#define readvll(x,N) vector<ll> (x)((N));for(int i=0;i<(N);i++){cin>>(x)[i];}
#define rep(i,N) for(ll (i)=0;(i)<(N);(i)++)
#define rep2d(i,j,H,W) for(ll (i)=0;(i)<(H);(i)++)for(ll (j)=0;(j)<(W);j++)
#define is_in(x,y) (0<=(x) && (x)<H && 0<=(y) && (y)<W)
#define yn {cout<<"Yes"<<endl;}else{cout<<"No"<<endl;}
#define double_out(x) fixed << setprecision(x)
template<class T> inline void erase_duplicate(vector<T>& A){sort(A.begin(),A.end());A.erase(unique(A.begin(),A.end()),A.end());}
inline ll powll(ll x,ll n){ll r=1;while(n>0){if(n&1){r*=x;};x*=x;n>>=1;};return r;}

inline bool NAND(bool P,bool Q){
  if(P && Q){
    return false;
  }else{
    return true;
  }
}

inline bool f(const vector<bool> C){
  return NAND(NAND(NAND(C[0],C[1]),C[2]),NAND(NAND(C[3],C[4]),C[5]));
}

int main(){
  const ll N=6;
  vector<string> A(N);
  for(ll i=0;i<N;i++){
    cin>>A[i];
  }
  ll M=1<<N;
  for(ll i=0;i<M;i++){
    vector<bool> B(N,false);
    for(ll j=0;j<N;j++){
      if((i>>j)&1){
        B[j]=true;
      }
    }
    if(f(B)){
      ll flag=0;
      for(ll j=0;j<N;j++){
        for(ll k=0;k<N;k++){
          if(A[j]==A[k] && B[j]!=B[k]){
            flag=1;
            break;
          }
        }
        if(flag==1){
          break;
        }
      }
      if(flag==0){
        cout<<"YES"<<endl;
        return 0;
      }
    }
  }
  cout<<"NO"<<endl;
}