#include <bits/stdc++.h>
using namespace std;
#define INF 1<<30
#define MAX 10005
#define FASTIO ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
typedef long long ll;

struct Item
{
    int value, weight;

    Item(int value, int weight) : value(value), weight(weight)
    {}
};

bool cmp(struct Item a, struct Item b)
{
    double r1 = (double) a.value / a.weight;
    double r2 = (double) b.value / b.weight;

    return r1 > r2;
}

double fractionalKnapsack(int W, struct Item ar[], int n)
{
    sort(ar, ar+n, cmp);

    int curWeight = 0;
    double finalValue = 0.0;

    for(int i = 0; i < n; i++){
        if(curWeight+ar[i].weight <= W){
            curWeight += ar[i].weight;
            finalValue += ar[i].value;
        }
        else{
            int remain = W - curWeight;
            finalValue += ar[i].value *( (double) remain/ar[i].weight );
            break;
        }
    }

    return finalValue;
}


int main()
{
    FASTIO
    ///*
    //double start_time = clock();
#ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
    freopen("error.txt", "w", stderr);
#endif
    //*/

    int W = 50;   //    Weight of knapsack
    Item arr[] = {{60, 10}, {100, 20}, {120, 30}};

    int n = sizeof(arr) / sizeof(arr[0]);

    cout << "Maximum value we can obtain = "
         << fractionalKnapsack(W, arr, n);
    return 0;

    //double end_time = clock();
    //printf( "Time = %lf ms\n", ( (end_time - start_time) / CLOCKS_PER_SEC)*1000);

    return 0;
}