SMMR-T151: De Facto Speed

#include <iostream>
#include <vector>
using namespace std;

#define lli long long

int nu;
vector<int> portal;

bool HighEnough(lli mul){
    lli re = mul * portal[1];
    for(int i = 2; i <= nu; ++i){
        lli nxt = re / (lli)portal[i];
        if(nxt == 0){
            return false;
        }
        re = nxt * portal[i];
    }
    return true;
}

int main(){

    scanf("%d", &nu);
    portal.assign(nu + 10, 0);
    for(int i = 1; i <= nu; ++i){
        scanf("%d", &portal[i]);
    }

    lli l = 1;
    lli r = 1e18;
    lli mn = 1e18;
    while(l <= r){
        lli m = (l + r) / 2;
        if(HighEnough(m)){
            mn = min(mn, m);
            r = m - 1;
        } else {
            l = m + 1;
        }
    }

    lli ans = mn * portal[1];
    cout << ans;

    return 0;
}