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

int longSubArrsum(int arr[], int n, int x){
    unordered_map<int,int> m;
    int pre_sum = 0, res = 0;
    for (int i = 0; i < n; i++){
        pre_sum += arr[i];
        if(pre_sum == x){
            res = i+1;
        }
        if(m.find(pre_sum) == m.end()){
            m.insert({pre_sum,i});        
        }
        if (m.find(pre_sum - x) != m.end()){
            res = max(res, i - m[pre_sum-x]);
        }
    }
    return res;
}

int main(){
    int arr[] = {4,3,8,1,2,5};
    cout<<longSubArrsum(arr,6,8);
}