#include<bits/stdc++.h>
using namespace std;
const int N = 10010;
int a[N];
double b[N];
double dp[2][N];
int main(){
	freopen("offer.in","r",stdin);
	freopen("offer.out","w",stdout); 
	int n, m;
	cin >> n >> m;
	for (int i = 1; i <= m; i ++){
		cin >> a[i] >> b[i];
		b[i] = 1 - b[i];
	}
	bool flag = 1;
	for (int i = 0; i <= n; i ++) dp[0][i] = 1;
	for (int i = 1; i <= m; i ++){
		for (int j = 0; j <= n; j++){
			if(j >= a[i]){
				dp[flag][j] = min(dp[1-flag][j], dp[1-flag][j-a[i]] * b[i]);
			}else{
				dp[flag][j] = dp[1-flag][j];
			}
		}
		flag = 1 - flag;
	}
	printf("%.1f%%", (1-dp[1-flag][n]) * 100);
	return 0;
}