/// @formatter:off
#include <bits/stdc++.h>
#include <experimental/iterator>
using namespace std;
#define overload3(_1, _2, _3, name, ...) name
#define rep1(n) for (decltype(n) _tmp = 0; _tmp < n; _tmp++)
#define rep2(i, n) for (decltype(n) i = 0; i < n; i++)
#define rep3(i, a, b) for (decltype(b) i = a; i < b; i++)
#define rep(...) overload3(__VA_ARGS__, rep3, rep2, rep1)(__VA_ARGS__)
struct IOSetup { IOSetup() noexcept { ios::sync_with_stdio(false); cin.tie(nullptr); cout << fixed << setprecision(10); cerr << fixed << setprecision(10); } } iosetup;
struct Print {
    ostream &os; const string sep; bool is_debug;
    Print(ostream &os, string sep, bool is_debug): os(os), sep(sep), is_debug(is_debug) {}
    void operator()(bool) { os << "\n"; }
    template<class Head, class... Tail> void operator()(bool is_first, Head &&head, Tail &&...tail) { os << head; if (not is_first and sizeof...(tail) != 0) os << sep; operator()(false, forward<Tail>(tail)...); }
    template<class T> void operator()(bool, vector<T> &vec) { copy(cbegin(vec), cend(vec), experimental::make_ostream_joiner(os, sep)); os << "\n"; }
    template<class T> void operator()(bool, vector<vector<T>> &vv) { size_t ind = 0; if (is_debug) os << "\n"; for (auto &vec: vv) { if (is_debug) os << ind++ << ": "; operator()(false, vec); } }
};
auto print_impl = Print(cout, " ", false);
#define print(...) print_impl(true, "", __VA_ARGS__)
#ifdef LOCAL
auto debug_impl = Print(cerr, " ", true);
#define debug(...) debug_impl(true, "(" #__VA_ARGS__ ") "s, __VA_ARGS__)
#else
#define debug(...)
#endif
template<class... T> void drop(const T &... x) { print(x...); exit(0); }
template <class T> bool chmax(T &a, const T &b) { return a < b and (a = b, true); }
template <class T> bool chmin(T &a, const T &b) { return a > b and (a = b, true); }
using i64 = long long;
using u64 = unsigned long long;
using f64 = long double;
// @formatter:on

int main() {
    size_t n;
    cin >> n;
    vector<int> p(n);
    for (auto &&elem: p) cin >> elem, elem--;

    map<int, size_t> index{};
    rep(i, n) index[p[i]] = i;
    int ans = 0;
    rep(i, n) {
        while (p[i] != i) {
            ans++;
            size_t j = (p[i] < i ? index[p[i] + 1] : index[p[i] - 1]);
            swap(p[i], p[j]);
            swap(index[p[i]], index[p[j]]);
        }
    }
    print(ans);
}