const unsigned int BAUD_RATE = 9600;
unsigned int keys = 0;

void setup() {
    Serial.begin(BAUD_RATE);
    Serial.print("> ");
}

void loop() {
    if (Serial.available() <= 0) {
        return;
    }

    Serial.write(Serial.read());
    keys++;

    if (keys == 100) {
        Serial.println("\nKABOOM!!!");
        keys = 0;
        Serial.print("> ");
        return;
    }

    Serial.println("");
    Serial.print(keys);
    Serial.println(" keys pressed");
    Serial.print("> ");
}