#include using namespace std; typedef pair pii; typedef long long ll; const int N = 2000086, MOD = 998244353, INF = 0x3f3f3f3f; int n, m, w[N]; int main() { cin >> n; for (int i = 1; i < n + 1; i++) scanf("%d", w + i); for (int i = 1; i < n; i++) if (w[i] == w[i + 1]) { puts("Yes"); return 0; } for (int i = 1; i < n - 1; i++) if (w[i] == w[i + 2]) { puts("Yes"); return 0; } puts("No"); return 0; }