#include using namespace std; #define REP(i,n) for(int i=0; i<(int)(n); i++) template class fenwick_tree { vector data; public: fenwick_tree() {} // manage data in [1, n] fenwick_tree(int n) : data(n + 1) {} void init() { fill(data.begin(), data.end(), 0); } // return sum in [1, i] T sum(int i){ T s = 0; while(i > 0){ s += data[i]; i -= i & -i; } return s; } // return sum in [l, r] T sum(int l, int r) { return sum(r) - sum(l-1); } void add(int i, T x){ while(i < (int)data.size()){ data[i] += x; i += i & -i; } } }; int main() { ios_base::sync_with_stdio(0); cin.tie(0); int n; cin >> n; int ret = 0; fenwick_tree tree(30000); REP (i, n) { int m; cin >> m; tree.add(m, 1); if (m == 1) ret += i; else ret += i - tree.sum(m-1); } cout << ret << endl; return 0; }