let c,b,a=" OO"," XXX"," 
---+---+---
 ";;for i=0to 6do
Printf.printf" X |   | %c%s%c | %c |  %s%c | %c | %c 

"c.[i/3]a b.[i/6]c.[min 1i]a b.[i/4]c.[i/5]b.[i/2]done