#[derive(Debug, Clone)] struct SegmentTree { n: usize, orgn: usize, unit: T, mem: Vec, operator: F } impl SegmentTree where T: std::fmt::Debug + Copy, F: Fn(T, T) -> T { fn new(n: usize, unit: T, operator: F) -> Self { let mut size = 1usize; while size < n { size *= 2; } Self { n: size, orgn: n, unit: unit, mem: vec![unit; size*2-1], operator: operator, } } fn find_closed(&self, l: usize, r: usize) -> T { self.find(l, r+1) } fn find(&self, l: usize, r: usize) -> T { self._find(l, r, 0, 0, self.n) } fn set(&mut self, pos: usize, val: T) { let mut pos = pos + self.n - 1; self.mem[pos] = val; while pos > 0 { pos = self._parent(pos); self.mem[pos] = (self.operator)(self.mem[self._left(pos)], self.mem[self._right(pos)]); } } fn get(&mut self, pos: usize) -> T { self.mem[pos + self.n - 1] } fn _find(&self, a: usize, b: usize, nodenum: usize, l: usize, r: usize) -> T { if r <= a || b <= l { return self.unit; } else if a <= l && r <= b { return self.mem[nodenum]; } let left = self._find(a, b, self._left(nodenum), l, (l+r)/2); let right = self._find(a, b, self._right(nodenum), (l+r)/2, r); (self.operator)(left, right) } fn _left(&self, k: usize) -> usize { 2*k+1 } fn _right(&self, k: usize) -> usize { 2*k+2 } fn _parent(&self, k: usize) -> usize { (k-1)/2 } } fn main() { let mut n = String::new(); std::io::stdin().read_line(&mut n).ok(); let n: usize = n.trim().parse().unwrap(); let mut a = String::new(); std::io::stdin().read_line(&mut a).ok(); let a: Vec = a.trim().split_whitespace().map(|s| s.parse::().unwrap()-1).collect(); let mut b = String::new(); std::io::stdin().read_line(&mut b).ok(); let b: Vec = b.trim().split_whitespace().map(|s| s.parse::().unwrap()-1).collect(); let mut revmap = vec![0usize; n]; for i in 0..n { revmap[b[i]] = i; } let mut segtree = SegmentTree::new(n, 0usize, |x, y| x + y); let mut result = 0usize; for i in 0..n { result += segtree.find(revmap[a[i]]+1, n); segtree.set(revmap[a[i]], 1); } println!("{}", result); }