#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define rep2(i, s, n) for (ll i = s; i <= (ll)(n); i++)
#define rep3(i, s, n, d) for (ll i = s; i <= (ll)(n); i += d)
#define rep4(i, s, n, d) for (ll i = s; i >= (ll)(n); i += d)
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<string> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<char> vc;
typedef vector<vc> vvc;
typedef vector<vvc> vvvc;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<vvll> vvvll;
typedef vector<vvvll> vvvvll;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<vvd> vvvd;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<bool> vb;
typedef vector<vd> vvb;
typedef vector<vvd> vvvb;
typedef vector<pair<int, int>> vpi;
typedef vector<pair<ll, ll>> vpll;
typedef priority_queue<int, vector<int>, greater<int>> pqi;
typedef priority_queue<vi, vector<vi>, greater<vi>> pqvi;
typedef priority_queue<ll, vector<ll>, greater<ll>> pqll;
typedef priority_queue<vll, vector<vll>, greater<vll>> pqvll;
typedef priority_queue<int, vector<int>, less<int>> rpqi;
typedef priority_queue<vi, vector<vi>, less<vi>> rpqvi;
typedef pair<int, int> P;
#define yes(ans) if(ans)cout << "yes"<< endl; else cout << "no" << endl
#define Yes(ans) if(ans)cout << "Yes"<< endl; else cout << "No" << endl
#define YES(ans) if(ans)cout << "YES"<< endl ;else cout << "NO" << endl
#define printv(vec) {rep(i, vec.size()) cout << vec[i] << ' '; cout << endl;}
#define printvv(vec) rep(i, vec.size()) {rep(j, vec[i].size()) cout << vec[i][j] << ' '; cout << endl;};
#define printvvv(vec) rep(i, vec.size()) { rep(j, vec[i].size()) { rep(k, vec[i][j].size()) cout << vec[i][j][k] << ' '; cout << "	"; }cout << endl; };
#define all1(x) x.begin(),x.end()
#define all2(x) x.rbegin(), x.rend()
#define so(x) sort(all1(x))
#define re(x) reverse(all1(x))
#define rso(x) sort(all2(x))
#define vco(x, a) count(all1(x), a)
#define per(x) next_permutation(all1(x))
#define iINF 2147483647
#define llINF 9223372036854775807
#define INF 1000000000000000000
#define mod 998244353
#define mod2 1000000007

int main() {
	string a, p, q; cin >> a >> p >> q;
	Yes(p != q);
}