First Repeating Element

int firstRepeated(int arr[], int n) {
    int ans=-1;
    set<int> myHash;
    for(int i=n-1;i>=0;i--){
        if(myHash.find(arr[i])!=myHash.end()){
            ans=i;
        }else
            myHash.insert(arr[i]);
    }
    if(ans!=-1)
        return ans+1;
    return ans;
}