_Follow along with the video_ --- ### Introduction In this lesson we are going to build a script to handle the **signing** and **claiming** process. We will sign a message using an account that is _included in the Merkle tree_. This **signature** will allow another person to claim the airdrop on behalf of the original account. ### Setup We can begin by navigating into the `/script` folder and creating a `Interact.s.sol` file. To get the*most recently deployed airdrop contract*, we will use DevOps tools from Cyfrin foundry-devops, which should be already installed in this project. ```solidity import { Script, console } from "forge-std/Script.sol"; import { DevOpsTools } from "foundry-devops/src/DevOpsTools.sol"; import { MerkleAirdrop } from "../src/MerkleAirdrop.sol"; contract ClaimAirdrop is Script { function run() external { } } ``` Within the `run` function, we'll retrieve the most recently deployed `MerkleAirdrop` contract address and pass this contract address to a function `claimAirdrop`: ```solidity function run() external { address mostRecentlyDeployed = DevOpsTools.get_most_recent_deployment("MerkleAirdrop", block.chainid); claimAirdrop(mostRecentlyDeployed); } ``` ### `claimAirdrop` The `claimAirdrop` function will take the deployed `MerkleAirdrop` address as a parameter. First, we need to broadcast the transaction on the blockchain by wrapping our code between `vm.startBroadcast` and `vm.stopBroadcast`. Next, we invoke the `MerkleAirdrop::claim` function, passing the following required parameters: - **CLAIMING_ADDRESS**: The default Anvil key for the claiming address, which must be present in the Merkle Tree specified in the `input.json` file. This file can be regenerated by running the `GenerateInput` script. - **AMOUNT_TO_COLLECT**: Set to `25 * 1e18`. - **proof**: An array of bytes from the `output.json` file. - **v, r, s**: The components of the signature, which can be obtained either by: 1. Using `vm.sign(userPrivateKey, digest)`. 2. Using `cast wallet sign`. Here is the function: ```solidity function claimAirdrop(address airdrop) public { vm.startBroadcast(); // v, r, s are retrieved in the following lesson MerkleAirdrop(airdrop).claim(CLAIMING_ADDRESS, AMOUNT_TO_COLLECT, proof, v, r, s); vm.stopBroadcast(); } ```