help whit the CapacitiveSensor library

hey I am trying to do a capacitive sensor and I follow the example bat it didn't compiled can you help me?

this is my code:

#include <CapacitiveSensor.h>

CapacitiveSensor cs_2_4 = CapacitiveSensor(2,4);
void setup()
{

Serial.begin(9600);
}

void loop()
{
long start = millis();
long total1 = cs_2_4.capacitiveSensor(30);

Serial.print(millis() - start);
Serial.print("\t");

Serial.println(total1);

delay(1000);
}

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ok I am sorry but can you help me?

If you had bothered to read my entire reply you would know what you need to do before I have any hope of helping you.