def time_complexity_operation(arr, complexity):
    if complexity == "constant":
        return arr[0]  # O(1)
    
    elif complexity == "linear":
        for item in arr:  # O(n)
            print(item)
    
    elif complexity == "quadratic":
        for i in arr:
            for j in arr:  # O(n^2)
                print(f"({i}, {j})")
    
    else:
        return "Unsupported complexity"

# Example usage:
arr = [5, 10, 15, 20, 25]
print("Constant:")
print(time_complexity_operation(arr, "constant"))

print("\nLinear:")
time_complexity_operation(arr, "linear")

print("\nQuadratic:")
time_complexity_operation(arr, "quadratic")