#pragma GCC target("avx2,avx") #pragma GCC optimize("O3") #pragma GCC optimize("unroll-loops") #include #include #include using namespace std; using namespace __gnu_pbds; using ll = long long; using ull = unsigned long long; using pii = pair; using pll = pair; #define rep(i, n) for(int i = 0; i < (n); ++i) #define all(x) (x).begin(),(x).end() constexpr char ln = '\n'; constexpr long long MOD = 1000000007; //constexpr long long MOD = 998244353; template inline bool chmax(T1 &a, T2 b) {if (a < b) {a = b; return true;} return false;} template inline bool chmin(T1 &a, T2 b) {if (a > b) {a = b; return true;} return false;} inline int topbit(int x) {return x == 0 ? -1 : 31-__builtin_clz(x);} inline int topbit(long long x) {return x == 0 ? -1 : 63-__builtin_clzll(x);} inline int botbit(int x) {return x == 0 ? 32 : __builtin_ctz(x);} inline int botbit(long long x) {return x == 0 ? 64 : __builtin_ctzll(x);} inline int popcount(int x) {return __builtin_popcount(x);} inline int popcount(long long x) {return __builtin_popcountll(x);} void print() {cout << "\n";} template void print(const T &x, const Args &... args) { cout << x << " "; print(args...); } /////////////////////////////////////////////////////////////////////////////////////////////////////////////// int main() { ios::sync_with_stdio(false); cin.tie(nullptr); auto solve1=[](const vector &A) { int N = A.size(); vector ret(N); vector dp(N+1); dp[0] = MOD; rep(i,N) { int ng = 0; int ok = N; while (abs(ng-ok)>1) { int mid = (ng+ok)/2; if (dp[mid]<=A[i]) ok = mid; else ng = mid; } ret[i] = ok; dp[ok] = A[i]; } return ret; }; auto solve2=[](const vector &A) { int N = A.size(); vector ret(N); vector dp(N+1,1e9); dp[0] = 0; rep(i,N) { ret[i] = lower_bound(all(dp),A[i]) - dp.begin(); dp[ret[i]] = A[i]; } return ret; }; int N; cin >> N; vector A(N); rep(i,N) cin >> A[i]; int ans = 0; auto B = solve1(A); reverse(all(A)); auto Brev = solve1(A); reverse(all(Brev)); rep(i,N) { chmax(ans,min(B[i],Brev[i])-1); print(i,B[i],Brev[i]); } reverse(all(A)); auto C = solve2(A); reverse(all(A)); auto Crev = solve2(A); reverse(all(Crev)); rep(i,N) { chmax(ans,min(C[i],Crev[i])-1); print(i,C[i],Crev[i]); } cout << ans << ln; }