Get it in the least amount of operators

Using the digits $(1, 2, 3, 4, 5, 6, 7, 8, 9)$ in numerical order and only the operators $(+, -)$ or no operator among them, what is the smallest number of operators among the digits that allows you to obtain $100$ as a result?

Example:

$1 + 2 + 34-5 + 67-8 + 9 = 100$ , in this configuration $6$ operators were used $(+, +, -, +, -, +)$ .