# Uses python3
import sys
def getBestItem(values, weights):
    maxValueWeight = 0
    bestItem = 0
    for i in range(len(values)):
        if weights[i] >0:
            if values[i]/weights[i] > maxValueWeight:
                maxValueWeight = values[i]/weights[i]
                bestItem = i
    return bestItem


def getOptimalValue(capacity, values, weights):
    totalValue = 0
    tempWeight = 0
    
    for _ in range(len(values)):
        if capacity==0:
            return totalValue
        i = getBestItem(values, weights)
        if weights[i] < capacity:
            tempWeight = weights[i]
        else:
            tempWeight = capacity
        totalValue = totalValue + tempWeight*values[i]/weights[i]
        weights[i] = weights[i]-tempWeight
        capacity = capacity-tempWeight
    return totalValue

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 = getOptimalValue(capacity, values, weights)
    print("{:.10f}".format(opt_value))