#include<bits/stdc++.h>
using namespace std;
int answer(vector&arr){
int n = arr.size();
if(n==0){
return 0;
}
int area;
int maximum = 0;
int i=0;
stacks;
while(i<n){
if(s.empty()==true || arr[s.top()]<=arr[i]){
s.push(i++);
}else{
int x = s.top();
s.pop();
if(s.empty()==false){
area = arr[x]*(i);
}else{
area = arr[x]*(i-s.top()-1);
}
maximum = max(maximum,area);
}
}
while(s.empty()==false){
int x = s.top();
s.pop();
if(s.empty()==false){
area = arr[x](i);
}else{
area = arr[x](i-s.top()-1);
}
maximum = max(maximum,area);
}
return maximum;
}
int main() {
int n;
cin>>n;
vectorarr;
for(int i=0;i<n;i++){
int y;
cin>>y;
arr.push_back(y);
}
return answer(arr);
}
what is the problem with this code?