hdu1203

/**/
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cctype>
#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <vector>
#include <string>
#include <stack>
#include <queue>

typedef long long LL;
using namespace std;

int n, m;
struct node
{
	int w;
	double pro, ave;
	bool operator <(const node &x)const{
		return ave > x.ave;
	}
}a[10005];

int main()
{
	//freopen("in.txt", "r", stdin);
	//freopen("out.txt", "w", stdout);

	while(scanf("%d %d", &n, &m) == 2){
		if(!n && !m) break;
		for (int i = 1; i <= m; i++){
			scanf("%d %lf", &a[i].w, &a[i].pro);
			a[i].ave = a[i].pro / a[i].w;
		}
		sort(a + 1, a + 1 + m);
		double ans = 1;
		for (int i = 1; i <= m; i++){
			if(a[i].w <= n){
				n -= a[i].w;
				ans *= (1.0 - a[i].pro);
			}
		}
		printf("%.1lf%%\n", 100.0 - ans * 100);
	}

	return 0;
}
/**/