>>222
じゃ、パーツだけ教えるよ

n
a[i]/13==0
a[i]/13==1
a[i]/13==2
a[i]%13
a[i]%13
a[i]%13
a[i]%13

または

n
a[i]&3==0
a[i]&3==1
a[i]&3==2
a[i]/4
a[i]/4
a[i]/4
a[i]/4

好きなほうを使ってくれ