int fibonacci(int n) {
if (n == 0) return 0;
if (n == 1) return 1;

int f0 = 0; // F(0)
int f1 = 1; // F(1)
int current;

for (int i = 2; i <= n; i++) {
current = f0+ f 1; / / F(n) = F(n-1) + F(n-2)
f0 = f1;
f1 = current;
}

return current;
}