fractional_knapsack

# Uses python3
import sys


def get_optimal_value(capacity, weights, values):
    value = 0
    # amounts = []

    ratios = [values[i]/weights[i] for i in range(n)]

    # we repeat n times
    for _ in range(n):
        if capacity == 0:
            return value

        # we select the maximum of the ratios index left ie. the one with some non null weight
        max_ratio = max([ratios[i] for i in range(n) if (weights[i] > 0)])
        # we retrieve the index index of that maximum ratio
        max_index = ratios.index(max_ratio)
        # then we calculate the maximum amount we can fill up the bag with
        amount = min(capacity, weights[max_index])
        # update the total value of that amount
        value += amount*values[max_index]/weights[max_index]
        # reduce the weight and write how much we put in
        weights[max_index] -= amount
        # amounts.append(amount)
        # finally we update the capacity of the bag
        capacity -= amount
    return value


if __name__ == "__main__":
    data = list(map(int, sys.stdin.read().split()))
    n, capacity = data[0:2]
    values = data[2:(2 * n + 2):2]
    weights = data[3:(2 * n + 2):2]
    opt_value = get_optimal_value(capacity, weights, values)
    print("{:.10f}".format(opt_value))