function check_price(){

     var dropdownIndex = document.getElementById('minimum_price').selectedIndex;
     var dropdownIndex2 = document.getElementById('minimum_price').selectedIndex;
     var dropdownValue = document.getElementById('minimum_price')[dropdownIndex].value;
     
     var dropdownIndex_max = document.getElementById('maximum_price').selectedIndex;
     var dropdownValue_max = document.getElementById('maximum_price')[dropdownIndex_max].value;
     if (parseInt(dropdownValue_max) <= parseInt(dropdownValue)){
        document.getElementById('maximum_price').selectedIndex = dropdownIndex2+1;
        return false;
        }
     return true;
        }

    function check_price_max(){

     var dropdownIndex = document.getElementById('minimum_price').selectedIndex;
     var dropdownValue = document.getElementById('minimum_price')[dropdownIndex].value;
     
     var dropdownIndex_max = document.getElementById('maximum_price').selectedIndex;
     var dropdownValue_max = document.getElementById('maximum_price')[dropdownIndex_max].value;
        var dropdownIndex2 = document.getElementById('maximum_price').selectedIndex;
        
     if (parseInt(dropdownValue_max) <= parseInt(dropdownValue)){
        document.getElementById('minimum_price').selectedIndex = dropdownIndex2-1;
        return false;
        }
     return true;
        }