Var i: Integer;
s: String;
begin
writeln('Введите текст');
readln(s);
for i:=1 to Length(s) do
begin
if s[i]=' ' then s[i]:='_';
end;
writeln(s);
end.

Var
    g: string;
    i: byte;
begin
    readln(g);
    i := 1;
    while g[i] = ' ' do delete(g,i,1);
    i := length(g);
    while g[i] = ' ' do begin delete(g,i,1); i := i - 1 end;
    i := 1;
    while i <= length(g) do begin
  if g[i] = ' ' then
   if g[i-1] = '*' then begin
    delete(g,i,1);
    i := i - 1;
   end
   else begin
    delete(g,i,1);
    insert('_',g,i);
   end;
  inc(i);
    end;
    writeln(g);
end.