I'm tired of counting possible ways! Aww

There are Two sets ,Set A{1,2,3,.......n} and Set B{ $a_{1}$ , $a_{2}$ .......... $a_{i}$ } .Assume a function to be a Set of bridge that associates each element of Set A to each element of Set B and no two brides can have same starting or end points, basically a one to one relation Every element of Set A and B has to be used. If $n=i=10$ , How many possible functions are there? In the image, 2 functions A and B are shown.