def find_lambda_jit(target, source):
    """
    Finds the longest subsequence of the target array, 
    starting from index 0, that is contained in the source array.
    Returns the length of that subsequence + 1.
    
    i.e. returns the length of the shortest subsequence starting at 0 
    that has not previously appeared.
    
    Args:
        target: NumPy array, perferable of type int.
        source: NumPy array, perferable of type int.
    
    Returns:
        Integer of the length.
        
    """
    
    source_size = source.shape[0]-1
    target_size = target.shape[0]-1
    t_max = 0
    c_max = 0

    for si in range(0, source_size+1):
        if source[si] == target[0]:
            c_max = 1
            for ei in range(1,min(target_size, source_size - si+1)):
                if(source[si+ei] != target[ei]):
                    break
                else:
                    c_max = c_max+1
                    
#                 if(si+ei>=source_size):
#                     break

            if c_max > t_max:
                t_max = c_max 
                
    return t_max+1