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const int MAX_DURATION = 32000;
const int MIN_DURATION = 2000;
const int MIN_SPEED = 0;
const int MAX_SPEED = 15;
int duration = MAX_DURATION + (speed - MIN_SPEED) * (MIN_DURATION - MAX_DURATION) / (MAX_SPEED - MIN_SPEED);
static int lastDuration;
if (lastDuration != duration) {
lastDuration = duration;
printf("\n%i", duration);
}