#include<stdio.h>
#include<string.h>
#define MAX(x,y)(x>y?x:y)
const int MAXN=10010;
double bag[MAXN];
int w[MAXN];
double v[MAXN];
double fv(double a,double b){
//    if(a==0)return b;
    double c=1-a,d=1-b;
    return 1-c*d;
}
int main(){
    int n,m;
    while(~scanf("%d%d",&n,&m),n||m){
        memset(bag,0,sizeof(bag));
        for(int i=0;i<m;i++)
                scanf("%d%lf",&w[i],&v[i]);
        for(int i=0;i<m;i++)
            for(int j=n;j>=w[i];j--)
                bag[j]=MAX(bag[j],fv(bag[j-w[i]],v[i]));//少了-w【i】 
                bag[n]*=100; 
        printf("%.1lf%%\n",bag[n]);
    }
    return 0;
}