int led = 10;
int sw1 = 5;
int sw2 = 6;
String a;
void setup() 
{
  pinMode(led, OUTPUT);
  pinMode(sw1, INPUT);
  pinMode(sw2, INPUT);
  Serial.begin(9600);
}
void loop() 
{
  int push1 = digitalRead(sw1);
  int push2 = digitalRead(sw2);
  if (push1 == 1)
{
  a += "h";
  delay(1000);
  Serial.println(a);
}
if (push2 ==1)
{
  a += "i";
  delay(1000);
  Serial.println(a);
}
if (a.length() >= 2)
{
if (a=="hi")
{
  digitalWrite(led, HIGH);
  delay(1000);
  Serial.println(a);
  Serial.println(a.length());
}
else
{
  digitalWrite(led, LOW);
  delay(1000);
  Serial.println(a);
  Serial.println(a.length());
}
}
}