#include <bits/stdc++.h>
using namespace std;
int main() {
int arr[]= {2,2,5,5,3,3};
int n=sizeof(arr)/sizeof(arr[0]);
int pairs=0;
unordered_map<int, int> mp;
int k=6;
for(int j=0;j<n;j++){
int rem=arr[j]%k;
if(mp.find((k-rem)%k)!=mp.end()){
pairs++;
}
mp[rem]++;
}
cout<<pairs;
return 0;
}
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