#!/bin/sh
decalage=$1; shift
decalage=`expr 0$decalage % 26`
input=abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
output=$input
while test $decalage -gt 0; do
  output=`echo $output|tr a-zA-Z b-zaB-ZA`
  decalage=`expr $decalage - 1`
done
cat "$@" | tr $input $output