CFBR #88 :: Problem C

uses
    SysUtils, Math;

var
    n, i, j, tt : longint;
    a : array[0..5010, 0..5010] of boolean;
    g : array[0..5010] of array of longint;
    ch : char;
    w : array[0..5010] of boolean;

procedure ok(a, b, c : longint);
begin
    write(a, ' ', b, ' ', c);
    halt(0);
end;

procedure dfs(v, c, f : longint);

var
    i, tt, tto : longint;

begin
    w[v] := true;
    tt := length(g[v]) - 1;
    for i := 0 to tt do begin
        tto := g[v][i];
        if c = 1 then begin
            if not w[tto] then dfs(tto, 2, v);
        end else
        if c = 2 then begin
            if a[tto][f] then ok(f, v, tto) else
            if not w[tto] then dfs(tto, 2, v);
        end;
    end;
end;

begin
    readln(n);
    for i := 1 to n do begin
        for j := 1 to n do begin
            read(ch);
            a[i][j] := ch = '1';
        end;
        readln;
    end;
    for i := 1 to n do
        for j := 1 to n do
            if a[i][j] then begin
                tt := length(g[i]);
                setlength(g[i], tt + 1);
                g[i][tt] := j;
            end;
    fillchar(w, sizeof(w), 0);
    for i := 1 to n do
        if not w[i] then dfs(i, 1, i);
    write(-1);
end.