hdu 1203 DP

//背包
//求拿到offer的概率，先算一份也拿不到的概率
//DP[j] = min(DP[j],DP[j-ai[i]] + bi[i])
//求出拿不到offer的最小概率，再拿一减
//memset很有问题，前一部分被置为1，后一部分是随机值
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;

#define MAX 10001
int n,m;
int ai[MAX + 1];
double bi[MAX + 1];
double DP[MAX + 1];
double c;

int main()
{
	while(scanf("%d%d",&n,&m) != EOF)
	{
		if(n == 0 && m == 0)
			break;
		for(int i = 1; i <= m; i++)
		{
			cin>>ai[i]>>bi[i];
		}
                //memset(DP,1,sizeof(DP));
		for(int i = 0; i < MAX; i++)
		{
			DP[i] = 1;
		}
		c = 1;
		for(int i = 1; i <= m; i++ )
		{
			for(int j = n; j >= ai[i]; j--)
			{
				DP[j] = min(DP[j],DP[j-ai[i]] * (1 - bi[i]));
				c = min(c,DP[j]);
			}
		}
		double x = (1-c) * 100;
		printf("%.1f%%\n",x);

	}
	return 0;
}