# include "bits/stdc++.h" using namespace std; using LL = long long; using ULL = unsigned long long; const double PI = acos(-1); templateconstexpr T INF() { return ::std::numeric_limits::max(); } templateconstexpr T HINF() { return INF() / 2; } template T_char TL(T_char cX) { return tolower(cX); }; template T_char TU(T_char cX) { return toupper(cX); }; const int vy[] = { -1, -1, -1, 0, 1, 1, 1, 0 }, vx[] = { -1, 0, 1, 1, 1, 0, -1, -1 }; const int dx[4] = { -1,0,1,0 }, dy[4] = { 0,-1,0,1 }; int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; } int d_sum(LL n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; } int d_cnt(LL n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; } LL gcd(LL a, LL b) { if (b == 0)return a; return gcd(b, a%b); }; LL lcm(LL a, LL b) { LL g = gcd(a, b); return a / g*b; }; # define ALL(qpqpq) (qpqpq).begin(),(qpqpq).end() # define UNIQUE(wpwpw) (wpwpw).erase(unique(ALL((wpwpw))),(wpwpw).end()) # define LOWER(epepe) transform(ALL((epepe)),(epepe).begin(),TL) # define UPPER(rprpr) transform(ALL((rprpr)),(rprpr).begin(),TU) # define FOR(i,tptpt,ypypy) for(LL i=(tptpt);i<(ypypy);i++) # define REP(i,upupu) FOR(i,0,upupu) # define INIT std::ios::sync_with_stdio(false);std::cin.tie(0) # pragma warning(disable:4996) int a[101010], n; struct BIT { int bit[202020]; void init() { REP(i, 202020)bit[i] = 0; } int sum(int i) { int s = 0; while (i > 0) { s += bit[i]; i -= i& -i; } return s; } void add(int i, int x) { while (i <= 202020) { bit[i] += x; i += i& -i; } } }; int main() { BIT bit; bit.init(); cin >> n; for (int i = 0; i < n; i++)cin >> a[i]; LL ans = 0; for (int j = 0; j < n; j++) { ans += j - bit.sum(a[j]); bit.add(a[j], 1); } cout << (ans % 2 == 0 ? "Yes" : "No") << endl; }