public with sharing class SaveAssetFromReportController {
    public String newId { get; private set; }
    
    public void init() {
        String eid = ApexPages.currentPage().getParameters().get('eid');
        newId = ApexPages.currentPage().getParameters().get('newid');
        
        Event__c e = [select Id, Asset_Manual_Count__c from Event__c where Id = :eid];
        e.Asset_Manual_ID__c = newId;
        if (e.Asset_Manual_Count__c == null) {
            e.Asset_Manual_Count__c = 1;
        } else {
            e.Asset_Manual_Count__c = e.Asset_Manual_Count__c + 1;
        }
        update e;
    }
}