OME 1993 Problem 2

In the arithmetic triangle below each number (apart from those in the first row) is the sum of the two numbers immediately above. $0 1 2 3 4 ... 1991 1992 1993$ $\, 1 3 5 7 ......\,\,\, 3983 3985$ $\,\, 4 8 12 .......... \,\, 7968$ ······································· Prove that the bottom number is a multiple of $1993$ .