Lab Cycle 1 — Control Flow, Loops & Functions

def calculate_series_sum(n):
    total_sum = 0
    terms = []
    
    for i in range(1, n + 1):
        if i % 2 != 0:  # Odd term (positive)
            total_sum += i
            terms.append(f"+{i}" if i > 1 else f"{i}")
        else:           # Even term (negative)
            total_sum -= i
            terms.append(f"-{i}")
            
    return total_sum, " ".join(terms)

def main():
    try:
        n = int(input("Enter number of terms (n >= 1): "))
        if n < 1:
            print("Please enter a positive integer greater than or equal to 1.")
            return
            
        total, series_str = calculate_series_sum(n)
        
        print(f"\nSeries: {series_str}")
        print(f"Summation up to {n} terms = {total}")
        
    except ValueError:
        print("Invalid input! Please enter a valid integer.")

if __name__ == "__main__":
    main()