#include using namespace std; int main(){ int n; cin >> n; vector a(n); bool ok = false; for(int i = 0; i < n; i++){ cin >> a[i]; if(i != 0)if(a[i] == a[i-1]){ ok = true; } } for(int i = 0; i < n; i++){ swap(a[i], a[i+1]); if(i+2 < n)if(a[i+1] == a[i+2])ok = true; if(i != 0)if(a[i] == a[i-1])ok = true; swap(a[i], a[i+1]); if(ok)break; } if(ok)cout << "Yes" << endl; else cout << "No" << endl; return 0; }