#include<iostream>
#include<unordered_map>
using namespace std;
int longestSubarrayWithSumZero(int arr[],int n,int k){
    unordered_map<int,int>m;
    int pre = 0;
    int len = 0;
    for(int i=0;i<n;i++){
        pre+=arr[i];
        if(pre == k){
            len = max(len,i+1);
        }
        if(m.find(pre-k)!= m.end()){
            len = max(len,(i-m[pre-k]));
        }
        else{
            m[pre]= i;
        }
    }
    return len;
}
int main(){
    int arr[] = {1,-1,5,-2,3};
    int n = sizeof(arr)/sizeof(int);
    int k = 3;
    int ans = longestSubarrayWithSumZero(arr,n,k);
    cout<<ans;
return 0;}