学步园

没什么说得。

program poj2039;
var
  n,i,j,k:longint;
  s:string;
  ans:array [0..21] of string;

begin
  repeat
    readln(n);
    if n=0 then break;
    readln(s);
    k:=length(s);
    for i:=1 to n do
      ans[i]:='';
    for i:=1 to (k-1) div n + 1 do
      if i and 1 = 1 then
        for j:=1 to n do
          if i*n-n+j<=k then
            ans[j]:=ans[j]+s[i*n-n+j]
                        else
                     else
        for j:=n downto 1 do
          if i*n-n+j<=k then
            ans[n-j+1]:=ans[n-j+1]+s[i*n-n+j];
    for i:=1 to n do
      write(ans[i]);
    writeln;
  until false;
end.