#include using namespace std; #define fast_io ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL) #define pb push_back #define int long long #define ll long long #define ld long double #define rep(i, n) for (ll i=0; i=0; i--) #define mem(v, ha) memset(v, ha, sizeof(v)) #define all(a) a.begin(), a.end() #define allr(a) a.rbegin(), a.rend() #define CLOCK cerr << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n"; typedef vector vi; typedef vector> vvi; typedef vector> vpi; typedef vector vc; #define no cout << "NO\n" #define yes cout << "YES\n" #define mp make_pair #define ff first #define ss second const ll M = 1e9 + 7; const ll mod = 998244353 ; const long double PI = 3.141592653589793238460; const int inf = (int)(1e9); // auto sum=[&](int use, int y){return use+y;}; void solve() { int N; cin >> N; string S; cin >> S; /* if (n == 1) { no; return; } if (n == 2) { if (s[0] == s[1]) yes; else no; return; } if (n == 3) { if (s[0] == s[1] || s[1] == s[2]) yes; else no; return; } if (n >= 4) yes;*/ if (N >= 4) { cout << "YES" << endl; } else if (N == 1) { cout << "NO" << endl; } else { // N==2, 3 bool ok = false; for (ll i = 0; i + 1 < N; i++) { if (S[i] == S[i + 1]) { ok = true; break; } } if (ok) { cout << "YES" << endl; } else { cout << "NO" << endl; } } } int32_t main() { #ifndef ONLINE_JUDGE freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout); #endif fast_io; int T = 1; // cin >> T; while (T--) { solve(); } }