Arduino program to input any integer number and print its table

Write a Arduino program to accept a integer number and print its multiplication table.

int a,i;
void setup()
{
  Serial.begin(9600);
}

void loop()
{
  if(Serial.available())
  {
     char c = Serial.read();
    String st="";
    if (isDigit(c)) 
    {
      st=st+c;
      a=st.toInt();
      for(i=1;i<=10;i++)
      {
        Serial.println(i*a);
      }
    }
  }
 
}