  Theoretically motivated smallness of the penguin amplitude in $B \to \pi \pi$
decays allowes to calculate the value of the unitarity triangle angle $\alpha
(\phi_2)$ with good accuracy. The relatively large branching ratio of the decay
into $\pi^0 \pi^0$ is explained by the large value of FSI phase difference
between $\Delta I = 1/2$ and $\Delta I = 3/2$ tree amplitudes.
