#include<iostream>
#include<cstring>
#include<cmath>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<deque>
#include <algorithm>

using namespace std;

#define mem(a,b) memset(a,b,sizeof a)
#define PII pair<int,int>
#define ll long long
#define ull unsigned long long
#define ft first
#define sd second
#define endl '\n'
#define PI acos(-1.0)
#define lcm(a,b) a/gcd(a,b)*b
#define INF_INT 0x3f3f3f3f
#define debug(a) cout<<#a<<"="<<a<<endl;
#define _for(i,a,b) for( int i=(a); i<(b); ++i)
#define _rep(i,a,b) for( int i=(a); i<=(b); ++i)

//inline void print(__int128 x){if(x<0){putchar('-');x=-x;}if(x>9) print(x/10);putchar(x%10+'0');}
int gcd(int a, int b){return b ? gcd(b, a % b) : a;}
int exgcd(int a, int b, int &x, int &y){if(!b){x = 1; y = 0;return a;}int d = exgcd(b, a % b, y, x);y -= (a/b) * x;return d;}
int qmi(int m, int k, int p){int res = 1 % p, t = m;while (k){if (k&1) res = res * t % p;t = t * t % p;k >>= 1;}return res;}
inline int read(){int s=0,x=1;char ch=getchar();while(ch<'0'||ch>'9') {if(ch=='-') x=-1; ch=getchar();}while(ch>='0'&&ch<='9'){s=s*10+ch-'0';ch=getchar(); }return s*x;} 

const int N = 1e6+7;

int n,m;

void solve()
{
    n = read();
    map<int,int> mp;
    _for(i,0,n){
        m = read();
        if(mp[m]){
            puts("No");
            return;
        }
        else{
            mp[m] = 1;
        }
    }
    puts("Yes");
    return;
}
int main()
{
    //ios::sync_with_stdio(0);
    int T = 1;
    // cin >> T;
    while(T--)
    {
        solve();
    }
    return 0;
} 

#include<iostream>
#include<map>
#include<vector>
#include<algorithm>
#include<set>
#include<queue>
#include<stack>
#include<math.h>
#include<time.h>
#include<deque>
#include<cstring>
#define ll long long
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define pb push_back
#define F first
#define S second
#define mp make_pair
#define MOD (ll)(1e9+7)
#define INF (ll)(1e18)
#define M 5000005
#define endl "\n"
#define AC ios::sync_with_stdio(0);cin.tie(0);
using namespace std;
ll fpow(ll x,ll y){
    ll r=1;
    while(y){
        if(y&1){
            r*=x;
            r%=MOD;
        }
        x*=x;
        x%=MOD;
        y>>=1;
    }
    return r;
}
ll gcd(ll x,ll y){
    if(y>x) swap(x,y);
    return y?gcd(y,x%y):x;
}

signed main(){
    AC;
    int n;
    int cnt[1005]={0};
    cin>>n;
    FOR(i,0,n){
        int x;
        cin>>x;
        cnt[x]++;
    }
    FOR(i,1,n+1){
        if(cnt[i]!=1){
            cout<<"No"<<endl;
            return 0;
        }
    }
    cout<<"Yes"<<endl;
}
