#include <cstdio>

 #include <cstring>

 #include <iostream>

 using namespace std;

 const int N = ;

 double dp[N];

 int main()

 {

     int n , m , a;

     double b;

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

         if(n ==  && m == ) break;

         memset(dp ,  , sizeof(dp));

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

             scanf("%d%lf" , &a , &b);

             for(int j = m ; j>=a ; j--){

                 double tmp = dp[j-a] + b - dp[j-a]*b;

                 dp[j] = max(dp[j] , tmp);

             }

         }

         printf("%.1f%%\n" , dp[m] * );

     }

     return ;

 }