#include<iostream>
#include<cstring>
#include<algorithm>
#define V 11111
#define N 1111
#define MAX(x,y) ((x)>(y)?(x):(y))
using namespace std;

double dp[V]; 
int c[N];      //每所学校花的钱
double w[N];   //概率

int main()
{	
	int n,v,i,j;
	while(~scanf("%d%d",&v,&n))
	{
		if(v==0&&n==0)break;
		for(i=0;i<n;i++)
		{
			scanf("%d%lf",&c[i],&w[i]);
		}
		memset(dp,0,sizeof(double)*(v+1));  //double型的初始化
		for(i=0;i<n;i++)
		{
			for(j=v;j>=c[i];j--) 
				dp[j] = MAX(dp[j],w[i]+(1.0-w[i])*dp[j-c[i]]);//动态方程
		}
		printf("%.1lf%%\n",dp[v]*100);
	}
	return 0;
}