<< When they “meet” (i.e., at some moment they are in the same point as in the PREVIOUS WERE NOT), they joyfully exclaim (“Oh, Bob!” or “Oh, Alice!” respectively).>>

Let this test:
L = 10   T = 10   va = 10  vb = 10
n = 1  type = 1 t[1] = 0,  d[1] = 10.

Alice and Bob "meet" 10 times at the SAME point,  so answer should be 1.
But, AC solution gives 10.

>> at some moment they are in the same point

>> at some moment

there are different moments for their meeting