var s:string;
    Pass:longint;
    i:byte;
function snt(x:longint):boolean;
var i:longint;
begin
    if x<2 then exit(false)
    else
       for i:=2 to round(sqrt(x)) do
          if x mod i=0 then exit(false);
    exit(true);
end;
procedure check(s:string);    
var i,j:byte;
    ss:string;
    n:longint;
begin            
    for i:=length(s) downto 1 do
    for j:=1 to (length(s)-i+1) do
    begin
        ss:=copy(s,j,i);
        val(ss,n);
        if snt(n) then
        begin
            if (n>pass) then pass:=n;
            break;
        end;
    end;
end;
procedure tachso(s:string);
begin
    ss:='';
    pass:=0;
    for i:=1 to (length(s)+1) do
    begin
        if s[i] in ['0'..'9'] then ss:=ss+s[i]
        else 
        begin
            if ss<>'' then 
                check(ss);
            ss:='';
        end;
    end;
end;
begin
    s:='test#1234.pass12';  //Doc chuoi tu File
    TachSo(s);
    write(pass);
    readln;
end.