for(;idx>0;idx-=idx&-idx)

sum+=tree[idx];

return sum;

vector<LL > b = a;

sort(all(b)),b.resize(unique(all(b))-b.begin());

for(auto &x:a)

x = lower_bound(all(b),x)-b.begin();

return a;

vector<LL > b = comp_number(a);

for(auto x:b)

upd(x,1);

for(int i=0;i<a.size();i++){

int num = read(b[i]-1);

if(k>num){

k-=num;

continue;

}

int idx = i+1;

while(k){

if(a[idx]<a[i] && --k == 0) return {a[i],a[idx]};

idx++;

}

}

return {-1, -1}; //No K-th inversions found!

}