### Exercise 1 Solution Let's go over the solution for the first exercise. First, we'll need to call the function `mint` on the contract `nonFungiblePositionManager`. The interface for `nonFungiblePositionManager` contains the `mint` function that we will call. The struct `MintParams` is what we'll need to pass in to call the function `mint`. ```javascript struct MintParams { address token0; address token1; uint24 fee; int24 tickLower; int24 tickUpper; uint256 amount0Desired; uint256 amount1Desired; uint256 amount0Min; uint256 amount1Min; address recipient; uint256 deadline; } ``` Back inside the exercise, we'll paste this struct into our code: ```javascript struct MintParams { address token0; address token1; uint24 fee; int24 tickLower; int24 tickUpper; uint256 amount0Desired; uint256 amount1Desired; uint256 amount0Min; uint256 amount1Min; address recipient; uint256 deadline; } ``` The contract that we need to call is called `nonFungiblePositionManager`. This contract inside this exercise is initialized as `manager`. We'll call the function `mint`, and then we'll need to pass in the struct. This will be called as: ```javascript manager.mint ``` We'll need to pass in the struct `nonFungiblePositionManager.MintParams` ```javascript nonFungiblePositionManager.MintParams ``` Then, we need to pass in the parameters. For token zero, we'll pass in `DAI`, and for token one, we'll pass in `WETH`. The pool fee for this DAI/WETH pool is 0.3%, so, we'll pass in `3000`. `tickLower` and `tickUpper` represent the price range that we are going to put liquidity into, and for this exercise it doesn't matter what we put in here as long as the `tickLower` and `tickUpper` are multiples of the tick spacing of the pool. The `tick_spacing` for this pool is 60. And we will use `max_tick` and `min_tick`, then round it to a multiple of `tick_spacing`. ```javascript int24 tickLower = MIN_TICK / TICK_SPACING * TICK_SPACING; int24 tickUpper = MAX_TICK / TICK_SPACING * TICK_SPACING; ``` When we divide `min_tick` by `tick_spacing` solidity division cuts off the remaining decimal parts, so we'll get a number that's a multiple of the `tick_spacing`, and then we'll multiply this number by the `tick_spacing` again. We'll do the same thing for `tickUpper`: ```javascript int24 tickUpper = MAX_TICK / TICK_SPACING * TICK_SPACING; ``` Then pass it as a parameter here: ```javascript tickLower: tickLower, tickUpper: tickUpper, ``` For amount zero desired, that's `DAI`, and for this exercise we were given `3000 DAI`. For here, I'll put `1000 DAI`, which is: ```javascript amount0Desired: 1000 * 1e18, ``` And token one will be `WETH`, and we were given `3 WETH`, so I will put `1 WETH` here, which is: ```javascript amount1Desired: 1e18, ``` Then amount zero min, we will set to zero, for simplicity: ```javascript amount0Min: 0, amount1Min: 0, ``` The recipient of this NFT, which represents this position, for this exercise, we will set it to this contract. This is done by: ```javascript recipient: address(this), ``` The deadline, we will set to the block timestamp: ```javascript deadline: block.timestamp ``` Now, let's execute exercise one. Inside the terminal we'll set the fork URL as an environment variable. To execute the test, we'll type: ```bash forge test --fork-url $FORK_URL --match-path test/uniswap-v3/exercises/UniswapV3Liquidity.test.sol ``` Furthermore, inside this contract, we have several exercises, and I only want to execute this test called `test_mint`. So I'll pass in an extra parameter called `--match-test`: ```bash forge test --fork-url $FORK_URL --match-path test/uniswap-v3/exercises/UniswapV3Liquidity.test.sol --match-test test_mint ``` Okay, and our test passed!