Using FORTRAN, Calculate the probability of being dealt $"21"$ on the initial Blackjack deal!!!

In the game of Blackjack, also known as twenty$-$one, a player receives two cards dealt from a standard deck of $52$ playing cards. A standard card deck is composed of four different suits $($spades$,$ hearts, diamonds, and clubs$)$ each of which contains $13$ cards of different rank or value. $.$