function addFirstBuyers(address[] _addresses, uint256[] _amount) public onlyOwner {
        require(_addresses.length == _amount.length);
        for(uint256 i = 0; i < _addresses.length; i++) {
            uint256 weightedContribution = (bst.balanceOf(_addresses[i]).mul(_amount[i])).div(10**18);

            FirstBuyer storage buyer = firstBuyers[_addresses[i]];
            uint256 before = buyer.tokensReceived;
            buyer.tokensReceived = buyer.tokensReceived.add(_amount[i]);
            buyer.weightedContribution = buyer.weightedContribution.add(weightedContribution);

            property.mintTokens(_addresses[i], _amount[i]);
            firstBuyers[_addresses[i]] = buyer;

            totalWeightedContribution = totalWeightedContribution.add(weightedContribution);
            if(before == 0) {
                firstBuyerIndex[numOfFirstBuyers] = _addresses[i];
                numOfFirstBuyers++;
            }
        }
    }