import java.io.IOException; import java.io.InputStream; import java.util.ArrayList; import java.util.Arrays; import java.util.HashSet; import java.util.NoSuchElementException; import java.util.Set; public class Main { public static void main(String[] args) { new Main().run(); } boolean exist(int xs,int ys,int B,int x,int y,Set set) { for (int xnb=xs*B;xnb<(xs+1)*B;++xnb) { for (int ynb=ys*B;ynb<(ys+1)*B;++ynb) { int dx=x-xnb; int dy=y-ynb; if (dx*dx+dy*dy>=20*20) continue; if (set.contains((long)xnb<<32|ynb)) return true; } } return false; } void run() { FastScanner sc=new FastScanner(); int N=sc.nextInt(); int B=5; int MAX=(20000+B-1)/B; boolean[][] es=new boolean[MAX][MAX]; Set set=new HashSet<>(); int[] X=new int[N]; int[] Y=new int[N]; for (int i=0;i=MAX||ys+dy>=MAX) continue; if (!es[xs+dx][ys+dy]) continue; if (exist(xs+dx,ys+dy,B,X[i],Y[i],set)) { continue out; } } } set.add((long)X[i]<<32|Y[i]); es[xs][ys]=true; ++ans; } System.out.println(ans); } 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;} public boolean hasNext() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; 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() { long nl = nextLong(); if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException(); return (int) nl; } public double nextDouble() { return Double.parseDouble(next());} }