#include using namespace std; #define rep(i,n) for(ll i=0;i<(n);++i) using ll = int_fast64_t; using pll = pair; constexpr ll INF = 1LL<<60; constexpr ll MOD = 1e9+7; template bool chmax(T &a,const T &b){if(a bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}return 0;} #if loc||local void dump(){cerr< void dump(T&& h, Ts&&... t){cerr<(t)...);} #else void dump(){} template void dump(T&& h, Ts&&... t){} #endif template istream &operator>>(istream&is,vector&v){for(auto &elemnt:v)is>>elemnt;return is;} template istream &operator>>(istream&is,pair&p){is>>p.first>>p.second;return is;} template ostream &operator<<(ostream& os,vectorconst& v){for(auto const& vi:v)os< ostream &operator<<(ostream& os,pairconst& p){os<vector vec(size_t a){return vector(a);} templateauto vec(size_t a, Ts... ts){return vector(ts...))>(a, vec(ts...));} signed main(){ int n = 4; vector a(n); cin>>a; vector b(n); iota(b.begin(),b.end(),1); cout<<(a==b?"Yes":"No")<