program DFS_1;

var
  Arid : array of array[0..1000] of integer;
  used : array of boolean;
  F : boolean;
  i, n, m, a, b : integer;

procedure DFS(p : integer; plast : integer = 0);
var i:integer;
begin
  used[p] := true;
  for i := 1 to Arid[p][0] do
    if (used[Arid[p][i]] = false) then
    begin
      plast := p;
      DFS(Arid[p][i], plast);
    end
    else
      if plast <> Arid[p][i] then
        F := false;
end;

begin
  read(n,m);
  if (n <= m) or (n - 1 <> m) or (n < 0) or (m < 0) then
  begin
    writeln('False');
  end
  else
  begin
    //************************
    setlength(Arid, n);
    setlength(used, n);
    F := true;
    //инициализация
    for i := 0 to n-1 do
    begin
      Arid[i][0] := 0;
      used[i] := false;
    end;

    for i := 0 to m-1 do
    begin
      read(a, b);
      Arid[a-1][0] += 1;
      Arid[a-1][Arid[a-1][0]] := b - 1;
      Arid[b-1][0] += 1;
      Arid[b-1][Arid[b-1][0]] := a - 1;
    end;

    DFS(0);

    for i := 0 to n-1 do
      if (used[i] = false) then F := false;


    if F then
      writeln('True')
    else
      writeln('False');
  end;
  read(i);
end.