/* #region header */ #pragma GCC optimize("O3") //コンパイラ最適化用 #ifdef LOCAL #define _GLIBCXX_DEBUG //配列に[]でアクセス時のエラー表示 #endif #define _USE_MATH_DEFINES #include //sort,二分探索,など #include //固定長bit集合 // #include // #include #include //assert(p)で,not pのときにエラー #include #include //実行時間計測 #include #include //pow,logなど #include //複素数 #include #include #include #include //sortのgreater #include //setprecision(浮動小数点の出力の誤差) #include // std::left, std::right #include //入出力 #include //集合演算(積集合,和集合,差集合など) #include #include //iota(整数列の生成),gcdとlcm,accumulate #include #include #include #include #include #include #include #include //pair #include using namespace std; typedef long long LL; typedef long double LD; #define ALL(x) x.begin(), x.end() const long long INF = numeric_limits::max() / 4; const int MOD = 1e9 + 7; // const int MOD=998244353; //略記 #define FF first #define SS second #define int long long #define stoi stoll #define LD long double #define PII pair #define PB push_back #define EB emplace_back #define MP make_pair #define SZ(x) (int)((x).size()) #define VB vector #define VVB vector> #define VI vector #define VVI vector> #define REP(i, n) for (int i = 0; i < (int)(n); i++) #define REPD(i, n) for (int i = (int)(n) - (int)1; i >= 0; i--) #define FOR(i, a, b) for (int i = a; i < (int)(b); i++) #define FORD(i, a, b) for (int i = (int)(b) - (int)1; i >= (int)a; i--) const int dx[4] = {0, 1, 0, -1}, dy[4] = {-1, 0, 1, 0}; const int Dx[8] = {0, 1, 1, 1, 0, -1, -1, -1}, Dy[8] = {-1, -1, 0, 1, 1, 1, 0, -1}; int in() { int x; cin >> x; return x; } // https://qiita.com/Lily0727K/items/06cb1d6da8a436369eed#c%E3%81%A7%E3%81%AE%E5%AE%9F%E8%A3%85 void print() { cout << "\n"; } template void print(Head &&head, Tail &&...tail) { cout << head; if (sizeof...(tail) != 0) cout << " "; print(forward(tail)...); } template void print(vector &vec) { for (auto &a : vec) { cout << a; if (&a != &vec.back()) cout << " "; } cout << "\n"; } template void print(set &set) { for (auto &a : set) { cout << a << " "; } cout << "\n"; } template void print(vector> &df) { for (auto &vec : df) { print(vec); } } // debug macro // https://atcoder.jp/contests/abc202/submissions/22815715 namespace debugger { template void view(const std::vector &a) { std::cerr << "{ "; for (const auto &v : a) { std::cerr << v << ", "; } std::cerr << "\b\b }"; } template void view(const std::vector> &a) { std::cerr << "{\n"; for (const auto &v : a) { std::cerr << "\t"; view(v); std::cerr << "\n"; } std::cerr << "}"; } template void view(const std::vector> &a) { std::cerr << "{\n"; for (const auto &p : a) std::cerr << "\t(" << p.first << ", " << p.second << ")\n"; std::cerr << "}"; } template void view(const std::map &m) { std::cerr << "{\n"; for (const auto &p : m) std::cerr << "\t[" << p.first << "] : " << p.second << "\n"; std::cerr << "}"; } template void view(const std::pair &p) { std::cerr << "(" << p.first << ", " << p.second << ")"; } template void view(const std::set &s) { std::cerr << "{ "; for (auto &v : s) { view(v); std::cerr << ", "; } std::cerr << "\b\b }"; } template void view(const T &e) { std::cerr << e; } } // namespace debugger #ifdef LOCAL void debug_out() {} template void debug_out(Head H, Tail... T) { debugger::view(H); std::cerr << ", "; debug_out(T...); } #define debug(...) \ do { \ std::cerr << __LINE__ << " [" << #__VA_ARGS__ << "] : ["; \ debug_out(__VA_ARGS__); \ std::cerr << "\b\b]\n"; \ } while (false) #else #define debug(...) (void(0)) #endif long long power(long long x, long long n) { // O(logn) // https://algo-logic.info/calc-pow/#toc_id_1_2 long long ret = 1; while (n > 0) { if (n & 1) ret *= x; // n の最下位bitが 1 ならば x^(2^i) をかける x *= x; n >>= 1; // n を1bit 左にずらす } return ret; } // @brief nCr. O(r log n)。あるいは前処理 O(n), 本処理 O(1)で求められる modint // の bc を検討。 int comb(int n, int r) { // https://www.geeksforgeeks.org/program-to-calculate-the-value-of-ncr-efficiently/ if (n < r) return 0; // p holds the value of n*(n-1)*(n-2)..., // k holds the value of r*(r-1)... long long p = 1, k = 1; // C(n, r) == C(n, n-r), // choosing the smaller value if (n - r < r) r = n - r; if (r != 0) { while (r) { p *= n; k *= r; // gcd of p, k long long m = __gcd(p, k); // dividing by gcd, to simplify // product division by their gcd // saves from the overflow p /= m; k /= m; n--; r--; } // k should be simplified to 1 // as C(n, r) is a natural number // (denominator should be 1 ) . } else p = 1; // if our approach is correct p = ans and k =1 return p; } // MOD void add(long long &a, long long b) { a += b; if (a >= MOD) a -= MOD; } template inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; } template inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; } // 負数も含む丸め long long ceildiv(long long a, long long b) { if (b < 0) a = -a, b = -b; if (a >= 0) return (a + b - 1) / b; else return a / b; } long long floordiv(long long a, long long b) { if (b < 0) a = -a, b = -b; if (a >= 0) return a / b; else return (a - b + 1) / b; } long long floorsqrt(long long x) { assert(x >= 0); long long ok = 0; long long ng = 1; while (ng * ng <= x) ng <<= 1; while (ng - ok > 1) { long long mid = (ng + ok) >> 1; if (mid * mid <= x) ok = mid; else ng = mid; } return ok; } // @brief a^n mod mod long long modpower(long long a, long long n, long long mod) { long long res = 1; while (n > 0) { if (n & 1) res = res * a % mod; a = a * a % mod; n >>= 1; } return res; } // @brief s が c を含むか template bool contain(const std::string &s, const T &c) { return s.find(c) != std::string::npos; } __attribute__((constructor)) void faster_io() { ios_base::sync_with_stdio(false); cin.tie(nullptr); cerr.tie(nullptr); } /* #endregion */ int n; signed main() { cin >> n; VI P(n); REP(ni, n) { cin >> P[ni]; } int ans = 0; REP(ni, n - 1) { FOR(nj, ni + 1, n) { if (P[ni] > P[nj]) ans++; } } print(ans); return 0; }