#include <bits/stdc++.h>

using namespace std;

#define ar array
#define ll long long

const int MAX_N = 1e5 + 1;
const ll MOD = 1e9 + 7;
const ll INF = 1e9;



void solve() {
    int n;
    cin>>n;
    vector<int> v(n);
    for(int i=0;i<n;i++){
        cin>>v[i];
    }
    sort(v.begin(),v.end());
    for(int i=1;i<n-1;i++){
        if(v[i]==v[i-1]){
            cout<<"No\n";
            return;
        }
    }
    cout<<"Yes\n";

}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int tc = 1;
    // cin >> tc;
    for (int t = 1; t <= tc; t++) {
        // cout << "Case #" << t  << ": ";
        solve();
    }
}
#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(ll i=a;i<b;i++)
#define pb push_back
typedef long long ll;
typedef long double ld;
const ll INF = 9223372036854775807;
const ll MOD = 1000000007;
const long double PI = acos(-1);
#define mp make_pair
#define all(v) v.begin(), v.end()
#define F first
#define S second
typedef vector<ll> vi;
typedef map<int, int> mii;
typedef vector<vi> vvi;

 //debugger
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

// debugger end
//global variables


//functions 

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    //int test;
   // cin>>test;
   // while(test--)
   // {
    //    solve();
    //}
   ll n;
   cin>>n;
   set<ll> s;

   rep(i,0,n)
   {
        ll temp;
        cin>>temp;

        if(temp>n)
        {
            cout<<"No"<<endl;
            return 0;
        }

        s.insert(temp);
   }


   if(s.size()==n)
   {
    cout<<"Yes"<<endl;
   }
   else
   {
    cout<<"No"<<endl;
   }


 return 0;
}