import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.util.ArrayList; import java.util.Arrays; import java.util.NoSuchElementException; public class Main { public static void main(String[] args) throws FileNotFoundException { long t = System.currentTimeMillis(); new Main().run(); System.err.println(System.currentTimeMillis() - t); } class SegTree{ int n=1; int[] v; public SegTree(int n) { while(this.n0) { k=(k-1)/2; v[k]=v[2*k+1]+v[2*k+2]; } } int query(int a,int b) { return query(0,n,a,b,0); } int query(int l,int r,int a,int b,int k) { if(a<=l&&r<=b)return v[k]; else if(r<=a||b<=l)return 0; else { int vl=query(l,(l+r)/2,a,b,2*k+1); int vr=query((l+r)/2,r,a,b,2*k+2); return vl+vr; } } } int pointer=0; void dfs(int cur,int par,int[] left,int[] right,ArrayList[] g) { left[cur]=pointer++; for(int dst:g[cur]) { if(dst==par)continue; dfs(dst,cur,left,right,g); } right[cur]=pointer++; } void run() { FastScanner sc = new FastScanner(); int N=sc.nextInt(); SegTree seg=new SegTree(2*N); ArrayList[] g=new ArrayList[N]; for(int i=0;i(); for(int i=0;i=0;--i) { ans+=seg.query(l[i], r[i]); seg.add(l[i], 1); seg.add(r[i], 1); } System.out.println(ans/2); } static void tr(Object... objects) { System.out.println(Arrays.deepToString(objects)); } } class FastScanner { private final InputStream in = System.in; private final byte[] buffer = new byte[1024]; private int ptr = 0; private int buflen = 0; private boolean hasNextByte() { if (ptr < buflen) { return true; }else{ ptr = 0; try { buflen = in.read(buffer); } catch (IOException e) { e.printStackTrace(); } if (buflen <= 0) { return false; } } return true; } private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;} private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;} private void skipUnprintable() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;} public boolean hasNext() { skipUnprintable(); return hasNextByte();} public String next() { if (!hasNext()) throw new NoSuchElementException(); StringBuilder sb = new StringBuilder(); int b = readByte(); while(isPrintableChar(b)) { sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } public long nextLong() { if (!hasNext()) throw new NoSuchElementException(); long n = 0; boolean minus = false; int b = readByte(); if (b == '-') { minus = true; b = readByte(); } if (b < '0' || '9' < b) { throw new NumberFormatException(); } while(true){ if ('0' <= b && b <= '9') { n *= 10; n += b - '0'; }else if(b == -1 || !isPrintableChar(b)){ return minus ? -n : n; }else{ throw new NumberFormatException(); } b = readByte(); } } public int nextInt() { return (int)nextLong(); } }