
    Write a function that analyzes a route identifier string and counts how many standard priority delivery segments exist within the complete delivery sequence, where each standard priority segment is denoted by 'std'. This count is essential for optimizing fleet resource allocation and route planning efficiency.
    

    
def count_occurance(s):
    """
    Write a function that analyzes a route identifier string and counts how many standard priority delivery segments exist within the complete delivery sequence, where each standard priority segment is denoted by 'std'. This count is essential for optimizing fleet resource allocation and route planning efficiency.
    

    """
def count_occurance(s):
    """
    Write a function that analyzes a route identifier string and counts how many standard priority delivery segments exist within the complete delivery sequence, where each standard priority segment is denoted by 'std'. This count is essential for optimizing fleet resource allocation and route planning efficiency.
    

    """
    count = 0
    for i in range(len(s) - 2):
        if s[i] == 's' and s[i + 1] == 't' and (s[i + 2] == 'd'):
            count = count + 1
    return count