#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int N;
    cin>>N;
    int T=N;
    int temp1,temp2;
    vector<int> vector1(N+1, 0);
    for(int i=1;i<=N;i++){
     cin>>temp1>>temp2;   
        vector1[i]=temp2;
    }
    temp1=1;
     for(int i=1;i<=N;i++){
       
        temp1=vector1[i]*temp1;
         
    }
    float hobba =temp1;
    cout<<hobba/1000000;
    return 0;
}