C Program Push button counts continuously when pushed for a long time

It counts from 0 to 3 only. Adds 1 when down is pressed and subtracts 1 when up is pressed. The problem is when i hold it, it counts continuously. I want it to count only once even if i hold the push button for a long time. I'm using ATMEL SAM3X microcontroller if that helps. And that the push buttons are logic 0.

#include "..\ASF\common\services\gpio\sam_gpio\sam_gpio.h"
#include "delay.h"
#include "sam3x_ek.h"
#include "Press_Counter.h"

signed int UP_DOWN;
signed int LEFT_RIGHT;

void Press_Counter()
{
    unsigned int Button_State;
    Button_State=1;

    if(UP)                  //if UP is pressed
    {
        delay_ms(50);
        if(Button_State==1)
        {
            UP_DOWN--;      //decrement
            if (UP_DOWN<0)
            {
                UP_DOWN=0;  // To ensure that the minimum value is 0
            }
        }
        Button_State=0;
    }

    else if(DOWN)           //if DOWN is pressed
    {
        delay_ms(50);
        if(Button_State==1)
        {
            UP_DOWN++;      //increment
            if (UP_DOWN>3)
            {
                UP_DOWN=3;  // To ensure that the maximum value is 3
            }
        }
        Button_State=0;
    }

    else
    {
        Button_State=1;
    }

    count_UP_DOWN=UP_DOWN;  // Get the value of counter cause imma use it later
}