{$mode objfpc}
        {$coperators on}
uses math;
var
        a,b:array[1..100] of longint;   x, y: boolean; n:longint;
procedure enter;
var i, j : longint;
        begin
                readln(n);
        end;
procedure solve;
var i, j,k : longint;
        begin
                x:=true; y:=true;
                for i:=1 to n do
                 begin
                        readln(a[i],b[i]);
                        if i>1 then if a[i]<>a[i-1] then x:=false;
                        if i>1 then if b[i]<>b[i-1] then y:=false;
                 end;
                if (x)or(y) then writeln('YES') else writeln('NO');
        end;
begin
        enter;
        Solve;
end.