// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

contract UnboundedRefund {
    address[] public users;
    mapping(address => uint256) public deposits;

    function deposit() external payable {
        if (deposits[msg.sender] == 0) users.push(msg.sender);
        deposits[msg.sender] += msg.value;
    }

    function refundAll() external {
        for (uint256 i = 0; i < users.length; i++) {
            address u = users[i];
            uint256 amt = deposits[u];
            if (amt > 0) {
                deposits[u] = 0;
                (bool ok, ) = payable(u).call{value: amt}("");
                require(ok, "refund failed");
            }
        }
    }
}