hdu 1203 I NEED A OFFER!

#include <iostream>
#include <cstring>
#include <algorithm>
#include <iomanip>
using namespace std;

#define N 11000

struct node
{
    int a;
    double b;
    bool operator < (const node &x) const
    {
        return a * x.b < b * x.a;
    }
};

int main ()
{
    int m, n;
    node stu[N];
    while (cin >> m >> n, m + n)
    {
        for (int i=0; i<n; i++)
            cin >> stu[i].a >> stu[i].b;

        sort (stu, stu + n);
        double ans = 1;
        for (int i=0; i<n; i++)
        {
            if (m - stu[i].a < 0)
                break;
            ans *= (1.0 - stu[i].b);
            m -= stu[i].a;
        }

        cout << setiosflags(ios::fixed)<< setprecision(1) << (1 - ans) * 100 << "%" << endl;
    }
    return 0;
}