149A - Business trip.cpp

//4032903   Jul 7, 2013 5:41:16 AM	fuwutu	 149A - Business trip	 GNU C++0x	Accepted	15 ms	0 KB
#include <iostream>
#include <algorithm>

using namespace std;

int main()
{
    int k, a[12], total(0);
    cin >> k;
    for (size_t i = 0; i < 12; ++i)
    {
        cin >> a[i];
        total += a[i];
    }

    if (total < k)
    {
        cout << -1 << endl;
    }
    else
    {
        sort(a, a + sizeof(a) / sizeof(a[0]), greater<int>());
        int sum = 0;
        int month = 0;
        while (sum < k)
        {
            sum += a[month];
            month += 1;
        }
        cout << month << endl;
    }

    return 0;
}