#define _USE_MATH_DEFINES #include using namespace std; #define FOR(i,m,n) for(int i=(m);i<(n);++i) #define REP(i,n) FOR(i,0,n) #define ALL(v) (v).begin(),(v).end() using ll = long long; constexpr int INF = 0x3f3f3f3f; constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL; constexpr double EPS = 1e-8; constexpr int MOD = 1000000007; // constexpr int MOD = 998244353; constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1}; constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1}; template inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; } template inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; } struct IOSetup { IOSetup() { std::cin.tie(nullptr); std::ios_base::sync_with_stdio(false); std::cout << fixed << setprecision(20); } } iosetup; template struct BIT { BIT(int n, const Abelian ID = 0) : n(n), ID(ID), dat(n, ID) {} void add(int idx, Abelian val) { while (idx < n) { dat[idx] += val; idx |= idx + 1; } } Abelian sum(int idx) const { Abelian res = ID; --idx; while (idx >= 0) { res += dat[idx]; idx = (idx & (idx + 1)) - 1; } return res; } Abelian sum(int left, int right) const { return left < right ? sum(right) - sum(left) : ID; } Abelian operator[](const int idx) const { return sum(idx, idx + 1); } int lower_bound(Abelian val) const { if (val <= ID) return 0; int res = 0, exponent = 1; while (exponent <= n) exponent <<= 1; for (int mask = exponent >> 1; mask > 0; mask >>= 1) { if (res + mask - 1 < n && dat[res + mask - 1] < val) { val -= dat[res + mask - 1]; res += mask; } } return res; } private: int n; const Abelian ID; std::vector dat; }; int main() { int n; cin >> n; vector a(n); REP(i, n) cin >> a[i]; multiset st(ALL(a)); for (int i = n - 1; i > 0; --i) { st.erase(st.lower_bound(a[i])); if (*st.rbegin() > a[i]) { vector b(a.begin(), a.begin() + i + 1); sort(ALL(b)); b.erase(unique(ALL(b)), b.end()); REP(j, i + 1) a[j] = lower_bound(ALL(b), a[j]) - b.begin(); int m = b.size(); ll inv = 0; BIT bit(m); REP(j, i + 1) { inv += bit.sum(a[j] + 1, m); bit.add(a[j], 1); } assert(inv > 0); REP(j, i + 1) { inv -= bit.sum(0, a[j]); inv += bit.sum(a[j] + 1, m); if (inv == 0) { cout << 1 << '\n'; return 0; } } cout << 2 << '\n'; return 0; } } cout << 0 << '\n'; return 0; }