最多1000个9999相乘，所以会用到高精度

#include<bits/stdc++.h>
using namespace std;

const int N=1010;

int n;
struct People{
    int a,b;
    bool operator <(const People &W)const {
        return a*b<W.a*W.b;
    }
}people[N];

vector<int> mul(vector<int> a,int b){
    int t=0;
    vector<int> res;
    for(int i=0;i<a.size()||t;i++){
        if(i<a.size()) t+=a[i]*b;
        res.push_back(t%10);
        t/=10;
    }
    return res;
}

vector<int> div(vector<int> a,int b){
    int r=0;
    vector<int> res;
    for(int i=a.size()-1;i>=0;i--){
        r=r*10+a[i];
        res.push_back(r/b);
        r%=b;
    }
    reverse(res.begin(),res.end());
    while(res.size()>1&&res.back()==0) res.pop_back();
    return res;
}

vector<int> max_vec(vector<int> a,vector<int> b){
    if(a.size()>b.size()) return a;
    if(a.size()<b.size()) return b;

    if( vector<int>(a.rbegin(),a.rend())>(vector<int> (b.rbegin(),b.rend()) ) ) return a;
    return b;
 }

int main(){
    cin>>n;

    for(int i=0;i<=n;i++){
        int a,b;
        cin>>a>>b;

        people[i]={a,b};
    }

    sort(people+1,people+n+1);

    vector<int> p(1,people[0].a);
    vector<int> res(1,0);
    for(int i=1;i<=n;i++){
        vector<int>  t=div(p,people[i].b);
        res=max_vec(res,t);

        p=mul(p,people[i].a);

    }

    for(int i=res.size()-1;i>=0;i--) cout<<res[i];
}