try this:
void loop
{
int val1 = digitalRead(switchPin1);
int val2 = digitalRead(switchPin2);
int val3 = digitalRead(switchPin3);
if (val1 == HIGH || val2 == HIGH || val3 == HIGH) {
if (val1 == HIGH) {
Serial.println(1);
delay(1000);
}
if (val2 == HIGH) {
Serial.println(2);
delay(1000);
}
if (val3 == HIGH) {
Serial.println(3);
delay(1000);
}
} else {
//none of the buttons are pressed
delay(1000);
Serial.println(0);
}
}
advise: try to learn millis() instead of delay() for timming