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README.md

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+# Pi Calculator
+
+This is a multi-threaded Rust program that calculates the first n digits of Pi using the Bailey–Borwein–Plouffe (BBP) formula. It uses arbitrary-precision arithmetic to ensure the accuracy of the calculated digits.
+
+## Features
+
+*   Calculates the first n digits of Pi.
+*   Multi-threaded to speed up the calculation.
+*   Configurable number of threads.
+*   Uses the BBP algorithm.
+*   High-precision calculation using the `rug` crate.
+
+## Building
+
+To build the program, you need to have Rust and Cargo installed. You can install them from [https://rustup.rs/](https://rustup.rs/).
+
+Once you have Rust and Cargo installed, you can build the program with the following command:
+
+```bash
+cargo build --release
+```
+
+## Usage
+
+To run the program, you can use the following command:
+
+```bash
+./target/release/pi <N> [OPTIONS]
+```
+
+### Arguments
+
+*   `<N>`: The number of digits of Pi to calculate.
+
+### Options
+
+*   `-t`, `--threads <THREADS>`: The number of threads to use. Defaults to 4.
+*   `-h`, `--help`: Print help information.
+*   `-V`, `--version`: Print version information.
+
+### Example
+
+To calculate the first 1000 digits of Pi using 8 threads, you can run the following command:
+
+```bash
+./target/release/pi 1000 -t 8
+```