#!/bin/bash

if [ "$1" == "--help" ] || [ "$1" -lt 1 ] || [ "$1" == "-h" ]; then
echo calculate fibunachi number for argument that bigger then 0 and less then 94
exit
fi

tmp=1
result=0

for (( i=1; $i<$1; i++))
do
    let "result = result + tmp"
    let "tmp = result - tmp"
done

echo "$result"