read n
read -d ""

LC_ALL=C
X=0
AB=`echo "${REPLY}" | tac`
B_CHK=`echo "${REPLY}" | awk '{print $2}' | grep -wc 1`

if [ $n -eq 1 ] && [ `echo "${REPLY}" | awk '{print $1}'` -eq 0 ]
then
	echo 0
	exit
fi

for i in `seq 2 $((n + 1))`
do
	A=`echo "${AB}" | awk -v NUM=$i 'NR==NUM {print $1}'`
	A=$((A + X))
	B=`echo "${AB}" | awk -v NUM=$i 'NR==NUM {print $2}'`

	if [ $A -gt $B ] > /dev/null 2>&1
	then
	        X=$(( X + $((B - $((A % B)) )) ))
	elif [ $A -lt $B ] > /dev/null 2>&1
	then
	        X=$(( X + $((B - A)) ))
	fi
done
echo $((X - B_CHK))
