int workbook(int n, int k, vector<int> arr) {
    int problems = 0;
    int bookMark = 1;
    
    for(int i = 0; i<arr.size(); i++){
        int pages = (arr[i] + k - 1) / k;
        int firs_exe = 1;
        int last_exe = min(firs_exe + k - 1, arr[i]);
        
        while (pages-->0) {
            
            if(firs_exe <= bookMark && bookMark <= last_exe) problems++;    
            
            firs_exe = last_exe + 1;
            last_exe = min(firs_exe + k - 1, arr[i]);
            bookMark++;
        }
    }
    
    return problems;
}