<?
$data = array(2,4,6,3,5,7,10,9,8,1,0);
$n = 0;
// assign
$maxmin = array($data[0],0,$data[0]);
//--------------------
// first compare
//--------------------
$i=1;
$max = $maxmin[0];
$min = $maxmin[2];
$gap = $max - $min;     //gap between max and min
$gapmax = $max - $data[$i]; //gapmax between max and data
$gapmin = $min - $data[$i]; //gapmin between min and data
//if abs| gapmax + gapmin | > $diff then it will be max or min
if(sqrt(pow($gapmax+$gapmin,2))>$gap){
    //select index to determine max or min value
    $index = ($gapmax+$gapmin)/sqrt(pow($gapmax+$gapmin,2))+1;
    $maxmin[$index] = $data[$i];
}
//--------------------
// second compare
//--------------------
$i++;
$max = $maxmin[0];
$min = $maxmin[2];
$gap = $max - $min;     //gap between max and min
$gapmax = $max - $data[$i]; //gapmax between max and data
$gapmin = $min - $data[$i]; //gapmin between min and data
//if abs| gapmax + gapmin | > $diff then it will be max or min
if(sqrt(pow($gapmax+$gapmin,2))>$gap){
    //select index to determine max or min value
    $index = ($gapmax+$gapmin)/sqrt(pow($gapmax+$gapmin,2))+1;
    $maxmin[$index] = $data[$i];
}
//--------------------
// third compare
//--------------------
$i++;
$max = $maxmin[0];
$min = $maxmin[2];
$gap = $max - $min;     //gap between max and min
$gapmax = $max - $data[$i]; //gapmax between max and data
$gapmin = $min - $data[$i]; //gapmin between min and data
//if abs| gapmax + gapmin | > $diff then it will be max or min
if(sqrt(pow($gapmax+$gapmin,2))>$gap){
    //select index to determine max or min value
    $index = ($gapmax+$gapmin)/sqrt(pow($gapmax+$gapmin,2))+1;
    $maxmin[$index] = $data[$i];
}
//--------------------
// 4th compare
//--------------------
$i++;
$max = $maxmin[0];
$min = $maxmin[2];
$gap = $max - $min;     //gap between max and min
$gapmax = $max - $data[$i]; //gapmax between max and data
$gapmin = $min - $data[$i]; //gapmin between min and data
//if abs| gapmax + gapmin | > $diff then it will be max or min
if(sqrt(pow($gapmax+$gapmin,2))>$gap){
    //select index to determine max or min value
    $index = ($gapmax+$gapmin)/sqrt(pow($gapmax+$gapmin,2))+1;
    $maxmin[$index] = $data[$i];
}
//--------------------
// 5th compare
//--------------------
$i++;
$max = $maxmin[0];
$min = $maxmin[2];
$gap = $max - $min;     //gap between max and min
$gapmax = $max - $data[$i]; //gapmax between max and data
$gapmin = $min - $data[$i]; //gapmin between min and data
//if abs| gapmax + gapmin | > $diff then it will be max or min
if(sqrt(pow($gapmax+$gapmin,2))>$gap){
    //select index to determine max or min value
    $index = ($gapmax+$gapmin)/sqrt(pow($gapmax+$gapmin,2))+1;
    $maxmin[$index] = $data[$i];
}
//--------------------
// 6th compare
//--------------------
$i++;
$max = $maxmin[0];
$min = $maxmin[2];
$gap = $max - $min;     //gap between max and min
$gapmax = $max - $data[$i]; //gapmax between max and data
$gapmin = $min - $data[$i]; //gapmin between min and data
//if abs| gapmax + gapmin | > $diff then it will be max or min
if(sqrt(pow($gapmax+$gapmin,2))>$gap){
    //select index to determine max or min value
    $index = ($gapmax+$gapmin)/sqrt(pow($gapmax+$gapmin,2))+1;
    $maxmin[$index] = $data[$i];
}
//--------------------
// 7th compare
//--------------------
$i++;
$max = $maxmin[0];
$min = $maxmin[2];
$gap = $max - $min;     //gap between max and min
$gapmax = $max - $data[$i]; //gapmax between max and data
$gapmin = $min - $data[$i]; //gapmin between min and data
//if abs| gapmax + gapmin | > $diff then it will be max or min
if(sqrt(pow($gapmax+$gapmin,2))>$gap){
    //select index to determine max or min value
    $index = ($gapmax+$gapmin)/sqrt(pow($gapmax+$gapmin,2))+1;
    $maxmin[$index] = $data[$i];
}
//--------------------
// 8th compare
//--------------------
$i++;
$max = $maxmin[0];
$min = $maxmin[2];
$gap = $max - $min;     //gap between max and min
$gapmax = $max - $data[$i]; //gapmax between max and data
$gapmin = $min - $data[$i]; //gapmin between min and data
//if abs| gapmax + gapmin | > $diff then it will be max or min
if(sqrt(pow($gapmax+$gapmin,2))>$gap){
    //select index to determine max or min value
    $index = ($gapmax+$gapmin)/sqrt(pow($gapmax+$gapmin,2))+1;
    $maxmin[$index] = $data[$i];
}
//--------------------
// 9th compare
//--------------------
$i++;
$max = $maxmin[0];
$min = $maxmin[2];
$gap = $max - $min;     //gap between max and min
$gapmax = $max - $data[$i]; //gapmax between max and data
$gapmin = $min - $data[$i]; //gapmin between min and data
//if abs| gapmax + gapmin | > $diff then it will be max or min
if(sqrt(pow($gapmax+$gapmin,2))>$gap){
    //select index to determine max or min value
    $index = ($gapmax+$gapmin)/sqrt(pow($gapmax+$gapmin,2))+1;
    $maxmin[$index] = $data[$i];
}
//--------------------
// 10th compare
//--------------------
$i++;
$max = $maxmin[0];
$min = $maxmin[2];
$gap = $max - $min;     //gap between max and min
$gapmax = $max - $data[$i]; //gapmax between max and data
$gapmin = $min - $data[$i]; //gapmin between min and data
//if abs| gapmax + gapmin | > $diff then it will be max or min
if(sqrt(pow($gapmax+$gapmin,2))>$gap){
    //select index to determine max or min value
    $index = ($gapmax+$gapmin)/sqrt(pow($gapmax+$gapmin,2))+1;
    $maxmin[$index] = $data[$i];
}

$result = ($maxmin[2]+$maxmin[0])/2;