#include<stdio.h>

 #include<string.h>

 #include<iostream>

 #include<math.h>

 using namespace std;

 int val[];

 double dp[],p[];

 double min(double a,double b)

 {

     if(a>b)

     return b;

     return a;

 }

 int main()

 {

     int n,m;

     while(scanf("%d %d",&n,&m),n+m)

     {

         for(int i=;i<=m;i++)

         {

             scanf("%d %lf",&val[i],&p[i]);

             p[i]=-p[i];

         }

         for(int i = ;i<=n;i++)

             dp[i] = 1.0;

         for(int i=;i<=m;i++)

         {

             for(int j=n;j>=val[i];j--)

             {

                 dp[j]=min(dp[j],dp[j-val[i]]*p[i]);

             }

         }

         printf("%.1lf%%\n",(-dp[n])*);

     }

     return ;

 }