program SODX;
 
var s, newStr, ans: ansistring;
    n, i: integer;
    j: char;
    fi, fo: text;
 
function palin(s: string): boolean;
var i, n: integer;
begin
    n := length(s);
    for i := 1 to n div 2 do
        if s[i] <> s[n-i+1] then exit(false);
    exit(true);
end;
 
begin
    assign(fi, 'SODX.inp'); reset(fi);
    assign(fo, 'SODX.out'); rewrite(fo);
    read(fi, s);
    n := Length(s);
    ans := '';
    for i := 0 to n do begin
        for j := '0' to '9' do begin
            newStr := copy(s, 1, i) + j + copy(s, i + 1, n);
            //iteln(newStr);
            // (palin(newStr)) then writeln('palin');
            if (palin(newStr)) AND ((ans = '') OR (newStr > ans)) then
                    ans := newStr;
			end;
		end;
    write(fo, ans);
    close(fi);
    close(fo);
end.

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