awk '
 FILENAME==ARGV[1] { x1=$0 }
 FILENAME==ARGV[2] { x2=$0 }
END {
x=length(x1)
print x

for (i=1;i<=x;i++)
{
	x11=x11""substr(x1,i,1)
	x22=x22""substr(x2,i,1)
	if(x11!=x22)
	{
		print x11"\n"x22
		exit
	}
}
} ' $1 $2
