// Code from Optimizing Arduino Code: no setup(), no loop()
// https://youtu.be/-XPrSScamXc
int main() {
// initialize digital pin LED_BUILTIN as an output.
DDRB = 0xff;
while (true) {
PINB = 0xff;
for (long i = 0; i < 500000; i++) {
asm("");
}
}
}