public class Temperature
{
   private double value = 0;
   private char unit = 'K';
   
   public Temperature(double value, char unit)
   {
       this.value = value;
       
       if ((unit == 'k') || (unit == 'K'))
          this.unit = 'K';
       else if ((unit == 'c') || (unit == 'C'))
          this.unit = 'C';
       else if ((unit == 'f') || (unit == 'F'))
          this.unit = 'F';
       else
          this.unit = 'I';
   }
   
   public String toString()
   {
       if (unit != 'I')
            return value + " " + unit;
       else
            return "invalid temperature";
   }
   
   public Temperature toCelsius()
   {
       if (unit == 'C')
          return new Temperature(value, unit);
       else if (unit == 'K')
          return new Temperature(value - 273, 'C');
       else if (unit == 'F')
          return new Temperature( 5.0/9.0*(value - 32.0), 'C');
       else
          return new Temperature(value, 'I');
   }
   
   public Temperature toFahrenheit()
   {
       if (unit == 'C')
          return new Temperature(9.0/5.0*value + 32.0, 'F');
       else if (unit == 'K')
          return new Temperature(9.0/5.0*(value-273) + 32.0, 'F');
       else if (unit == 'F')
          return new Temperature(value, unit);
       else
          return new Temperature(value, 'I');
   }
   
   public Temperature toKelvin()
   {
       if (unit == 'C')
          return new Temperature(value + 273, 'K');
       else if (unit == 'K')
          return new Temperature(value, unit);
       else if (unit == 'F')
          return new Temperature( 5.0/9.0*(value - 32.0) + 273, 'K');
       else
          return new Temperature(value, 'I');
   }
   
   
}