import std.stdio;
import std.file;
import std.conv;
import std.string:munch;
import std.math;
import std.regex;

class Segment{
    int x1, x2;
    double m, b;

    this( int x1, int y1, int x2, int y2 ){
        this.x1 = x1;
        this.x2 = x2;
        this.m = (y2 - y1)/cast(double)(x2 - x1);
        this.b = m * (0 - x1) + y1;
    }

    bool intersects(Segment s){
        if ( abs( this.m - s.m ) < .001 )
            return false;
        double x = -(this.b - s.b)/(this.m - s.m);
        return (x - this.x1)*(x - this.x2) < -.0001 && (x - s.x1)*(x - s.x2) < -.0001;
    }
}

struct Globals{
    int[][] knightMoves = [[2, 1], [2, -1], [-2, 1], [-2, -1],
                                 [1, 2], [1, -2], [-1, 2], [-1, -2]];
    int[][] comp;
    Segment[] segList;
    int N;
    int idx = 0;
    string[] nums;
}

static bool isOpen( Segment seg, ref Globals g ) {
    foreach( Segment s ; g.segList )
      if(seg.intersects(s))
        return false;
    return true;
}

static bool legal( int x, int y, ref Globals g ) {
    return x >= 0 && y >= 0 && x <= g.N && y <= g.N;
}

static bool wins( ref Globals g ) {
    for (int y = 1; y < g.N; y++)
       if (g.comp[0][y] > 0)
         for (int y2 = 1; y2 < g.N; y2++)
           if (g.comp[0][y] == g.comp[g.N][y2])
             return true;
    return false;
}

static bool solve( string f, ref Globals g ) {
    int newComp = 1;
    int M = nextInt( g );
    munch( f, " \t\n\r" );
    g.comp = new int[][](g.N+1, g.N+1);
    for (int i = 0; i < M; i++) {
      int player = (i % 2 == 0) ? 1: -1;
      int x = nextInt( g ), y = nextInt( g );
      g.comp[x][y] = player * newComp++;
      foreach(int[] del ; g.knightMoves) {
        int kx = x + del[0], ky = y + del[1];
        if( !legal( kx, ky, g ) )
          continue;
        int otherComp = g.comp[kx][ky];
        Segment seg = new Segment( x, y, kx, ky );
        if( otherComp * player > 0 && isOpen( seg, g ) ) {
          g.segList ~= seg;
          if (otherComp != g.comp[x][y])
            for(int px = 0; px <= g.N; px++)
              for (int py = 0; py <= g.N; py++)
                if (g.comp[px][py] == otherComp)
                  g.comp[px][py] = g.comp[x][y];
        }
      }
    }
    return wins( g );
}

int nextInt( ref Globals g ){
    int next = to!int( g.nums[ g.idx++ ] );
    return next;
}

void main(){
    auto file = File("connect.in", "r");
    auto r = regex( "\\s" );
    string[] nums;
    string f = "";
    Globals g;

    foreach(string line; lines( file )){
        f ~= line; // throw the lines into a string
    }

    g.nums = split( f, r );

    g.N = nextInt( g );
    while(g.N > 0){
        writeln( solve( f, g ) ? "yes" : "no" );
        g.N = nextInt( g );
    }
}