How many letters in the greeck alphabet?

Αα Alpha Νν Nu

Ββ Beta Ξξ Xi

Γγ Gamma Οο Omicron

Δδ Delta Ππ Pi

Εε Epsilon Ρρ Rho

Ζζ Zeta Σσς Sigma

Ηη Eta Ττ Tau

Θθ Theta Υυ Upsilon

Ιι Iota Φφ Phi

Κκ Kappa Χχ Chi

Λλ Lambda Ψψ Psi

Μμ Mu Ωω Omega