contract CO2Certificate {
    using SafeMath for uint256;

    uint256 private _burnedTokens;
    uint256 private _certifiedKilometers;
    string  private _ownerName;

    constructor (uint256 burnedTokens, uint256 certifiedKilometers, string ownerName) public {
        require (burnedTokens > 0, "You must burn at least one token");
        require (certifiedKilometers >= 0, "Certified Kilometers must be positive");
        
        _burnedTokens = burnedTokens;
        _certifiedKilometers = certifiedKilometers;
        _ownerName = ownerName;
    }

    // Getters
    function getBurnedTokens() public view returns(uint256) {
        return _burnedTokens;
    }

    function getCertifiedKilometers() public view returns(uint256) {
        return _certifiedKilometers;
    }

    function getOwnerName() public view returns(string) {
        return _ownerName;
    }

}
// CO2 Certificate "struct"
function getBurnedTokens() public view returns(uint256) {
    return _burnedTokens;
}

// Getters