#include"iostream"

 #include"stdio.h"

 #include"algorithm"

 #include"string.h"

 #include"cmath"

 #include"queue"

 #define mx 10005

 using namespace std;

 int price[mx];

 double chance[mx];

 double dp[mx];

 int main()

 {

     int n,m,i,j,k;

     while(cin>>n>>m,n||m)

     {

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

         {

             cin>>price[i]>>chance[i];

             chance[i]=-chance[i];

         }

         for(i=;i<=n;i++) dp[i]=;

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

         {

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

             {

                 if(dp[j]>dp[j-price[i]]*chance[i])dp[j]=dp[j-price[i]]*chance[i];

             }

         }

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

     }

     return ;

 }