#include <JC_Button.h> // https://github.com/JChristensen/JC_Button

Button button_increase( 4 );
Button button_decrease( 5 );

void setup()
{
  Serial.begin( 115200 );
  button_increase.begin();
  button_decrease.begin();
}

void loop()
{
  button_increase.read();
  button_decrease.read();

  static const uint8_t times[] = { 5, 10, 20, 30, 60, 120 };
  static const uint8_t times_count = sizeof( times ) / sizeof( times[0] );
  static int8_t index = 0;
  static int8_t index_previous = -1;

  if ( index < times_count - 1 && button_increase.wasReleased() )
  {
    ++index;
  }
  else if ( index > 0 && button_decrease.wasReleased() )
  {
    --index;
  }

  /* alternative behavior
  if ( button_increase.wasReleased() && ++index == times_count )
  {
    index = 0;
  }
  else if ( button_decrease.wasReleased() && --index == -1 )
  {
    index = times_count - 1;
  }
  */

  if ( index_previous != index )
  {
    index_previous = index;

    uint8_t time = times[index];

    Serial.print( "time = " );
    Serial.println( time );
  }
}