#include #define rep(i,n) for(int i=0;i<(n);i++) using namespace std; using lint=long long; template class Fenwick_tree{ vector a; public: Fenwick_tree(int n):a(n){} void add(int i,G val){ for(i++;i<=a.size();i+=i&-i) a[i-1]+=val; } G sum(int l,int r)const{ if(l==0){ G res{}; for(;r>0;r-=r&-r) res+=a[r-1]; return res; } return sum(0,r)-sum(0,l); } int lower_bound(G val)const{ if(val<=G{}) return 0; int x=0,k; for(k=1;k<=a.size();k<<=1); for(k>>=1;k>0;k>>=1) if(x+k<=a.size() && a[x+k-1]>=1;k>0;k>>=1) if(x+k<=a.size() && a[x+k-1]<=val) val-=a[x+k-1], x+=k; return x; } }; template long long inversion_number(const vector& a){ auto X=a; sort(X.begin(),X.end()); X.erase(unique(X.begin(),X.end()),X.end()); long long res=0; Fenwick_tree F(X.size()); rep(i,a.size()){ int x=lower_bound(X.begin(),X.end(),a[i])-X.begin(); res+=F.sum(x+1,X.size()); F.add(x,1); } return res; } int main(){ int n; lint k; scanf("%d%lld",&n,&k); vector a(n); rep(i,n) scanf("%d",&a[i]); lint t=inversion_number(a); puts(t<=k&&(k-t)%2==0?"YES":"NO"); return 0; }