Output of value-added value-added

[Saumya]

There's a costing code, depending on the amount applied with different discounts. The final value now appears after the click on the button. How to make the sum immediately available when entering the number input?

$(function() {
  function count() {
    var
      a = 49,
      b = 99,
      c = 99999,
      sum = +$("#count_inp").val() || 0,
      cost = 0,
      $result = $("#result p");
if (sum <= a) {
  cost = sum * 1;
} else if (sum > a && sum <= b) {
  cost = (sum - (sum / 10 / 2)) ;
} else if (sum > b && sum <=c) {
  cost = (sum - (sum / 10));
} else {
  
}

renderCost(cost)

}
function renderCost(value) {

$("#result p").html(value === 0 ? 'Укажите расстояние' : value + " Рублей")

}
var s = $("#process_all_b");

s.click(count)

});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.2/jquery.min.js"></script>

<div id="calc_div">

&lt;div id="quantity_div"&gt;&lt;p class="c"&gt;
    Укажите желаемую сумму сертификата&lt;br&gt;
    &lt;input type="text" id="count_inp"&gt;&lt;br&gt;
&lt;/div&gt;

&lt;div id="final_div"&gt;
    &lt;p class="c"&gt;&lt;button id="process_all_b" &gt;Посчитать&lt;/button&gt;&lt;br&gt;&lt;/p&gt;
    &lt;div id="result"&gt;&lt;p class="c"&gt;0 Рублей&lt;/p&gt;&lt;/div&gt;
&lt;/div&gt;

</div>

[kalyn]

You can use it. on('input') instead submit()♪

$(function() {
  function count() {
    var
      a = 49,
      b = 99,
      c = 99999,
      sum = +$("#count_inp").val() || 0,
      cost = 0,
      $result = $("#result p");
if (sum <= a) {
  cost = sum * 1;
} else if (sum > a && sum <= b) {
  cost = (sum - (sum / 10 / 2)) ;
} else if (sum > b && sum <=c) {
  cost = (sum - (sum / 10));
} else {
  
}

renderCost(cost)

}
function renderCost(value) {

$("#result p").html(value === 0 ? 'Укажите расстояние' : value + " Рублей")

}
$("#quantity_div").on('input', count);

});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.2/jquery.min.js"></script>

<div id="calc_div">

&lt;div id="quantity_div"&gt;&lt;p class="c"&gt;
    Укажите желаемую сумму сертификата&lt;br&gt;
    &lt;input type="text" id="count_inp"&gt;&lt;br&gt;
&lt;/div&gt;

&lt;div id="final_div"&gt;
    &lt;div id="result"&gt;&lt;p class="c"&gt;0 Рублей&lt;/p&gt;&lt;/div&gt;
&lt;/div&gt;

</div>