为什么我用int就过了

#include<iostream>
#include<climits>
#define maxn 1000010
#define ll long long
using namespace std;

ll n,a[maxn],l[maxn],r[maxn],lans[maxn],rans[maxn],ans=INT_MIN;

void luogu(){
    for(int i=0;i<=n+1;i++){
        l[i]=INT_MIN;
        r[i]=INT_MIN;
        lans[i]=INT_MIN;
        rans[i]=INT_MIN;
    }
}

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	
	cin>>n;
    luogu();
	for(ll i=1;i<=n;i++)cin>>a[i];
	for(ll i=1;i<=n;i++){
        l[i]=max(a[i],l[i-1]+a[i]);
        lans[i]=max(l[i],lans[i-1]);
    }
	for(ll i=n;i>=1;i--){
        r[i]=max(a[i],r[i+1]+a[i]);
        rans[i]=max(r[i],rans[i+1]);
    }
	for(ll i=2;i<n;i++)ans=max(ans,lans[i-1]+rans[i+1]);
	cout<<ans<<'\n';
	
	return 0;
}