#include <bits/stdc++.h>
using namespace std;
int rnk[1001];
int parnt[1001];
bool prim[100001];
void seive() {
  prim[0] = prim[1] = 1;
  for (unsigned long long i = 2; i < 100001; i++) {
    if (prim[i] == 0) {
      for (unsigned long long j = i * i; j < 100001; j += i) prim[j] = 1;
    }
  }
}
int findparnt(int x) {
  if (parnt[x] == x) return x;
  return parnt[x] = findparnt(parnt[x]);
}
bool iscon(int x, int y) { return (findparnt(x) == findparnt(y)); }
void conn(int x, int y) {
  int px = findparnt(x);
  int py = findparnt(y);
  if (px == py) return;
  if (rnk[px] > rnk[py]) {
    parnt[py] = px;
  } else if (rnk[px] < rnk[py]) {
    parnt[px] = py;
  } else {
    rnk[px]++;
    parnt[py] = px;
  }
}
long long gcd(long long x, long long y) {
  if (x % y == 0) return y;
  return gcd(y, x % y);
}
unsigned long long fastpow(unsigned long long b, unsigned long long p) {
  if (p == 0) return 1;
  unsigned long long t = fastpow(b, p / 2);
  if (p % 2 == 0) return t * t;
  return t * t * b;
}
unsigned long long lcm(unsigned long long a, unsigned long long b) {
  return ((a * b) / gcd(a, b));
}
double dis(double x, double y, double x1, double y1) {
  return sqrt((x - x1) * (x - x1) + (y - y1) * (y - y1));
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie();
  string s;
  int x;
  cin >> x >> s;
  set<char> v;
  for (long long(i) = (0); (i) < (s.size()); ++(i)) {
    v.insert(s[i]);
  }
  if (s.size() == v.size() && x != 1) return cout << "No", 0;
  cout << "Yes";
}
