var base = "mem_";
var loop = new Array('01', '02', '04', '05','06', '07', '08', '09', '10', '11', '13', '14', '15', '16', '17', '18', '19', '20', '21', '22', '23', '24', '25', '26','27', '28', '29','30','34');
var p_out_img = "page_parts/button_prev-dis.gif";
var n_out_img = "page_parts/button_next-dis.gif";

var prev_l = next_l = ''; 
var suffix = '';

function prev_alert() {
  alert('最初の選手です');
}

function next_alert() {
  alert('選手の末尾です');
}

function check_loop() {
  var url = location.href;
  var fname = url.split('/').pop().split('.');
  suffix = fname[1];
  var fnum = fname[0].split(base).pop();
  var ll = loop; var flag = 0;
  while(ll.length != 0 && flag < 2) {
    var num = ll.shift();
    if (num == fnum) {
      flag = 1;
    }
    else {
      if (flag == 0) {
	prev_l =  num;
      }
      else {
	next_l = num;
	flag = 2;
      }
    }
  }
  if (prev_l == '') {
    document.getElementById('prev').src = p_out_img;
  }
  if (next_l == '') {
    document.getElementById('next').src = n_out_img;
  }
}

function loop_prev() {
  if (prev_l != '') {
    location.href = base+prev_l+'.'+suffix;
  }
  else {
    prev_alert();
  }
}

function loop_next() {
  if (next_l != '') {
    location.href = base+next_l+'.'+suffix;
  }
  else {
    next_alert();
  }
}