def find_median(arr):
    n = len(arr)
    if n % 2 == 1:
        return arr[n // 2]
    else:
        return (arr[n // 2] + arr[n // 2 - 1]) / 2

def interQuartile(values, freqs):
    expanded_data = []
    for i in range(len(values)):
        expanded_data.extend([values[i]] * freqs[i])
    expanded_data.sort()
    q2 = find_median(expanded_data)
    n = len(expanded_data)
    if n % 2 == 1:
        lower_half = expanded_data[:n // 2]  
        upper_half = expanded_data[n // 2 + 1:]  
    else:
        lower_half = expanded_data[:n // 2]  
        upper_half = expanded_data[n // 2:]  
    q1 = find_median(lower_half)
    q3 = find_median(upper_half)
    iqr = q3 - q1
    print(f"{iqr:.1f}")