void merge(vector<int>&arr,int l,int mid,int h)
{
   vector<int>temp;
   int i=l;
   int j=mid+1;
while(i<=mid and j<=h)
{
    if(arr[i]<=arr[j])
    {
        temp.push_back(arr[i]);
        i++;
    }
    else 
    {
        temp.push_back(arr[j]);
        j++;
    }
}
while(i<=mid)
{
    temp.push_back(arr[i]);
    i++;
}
while(j<=h)
{
    temp.push_back(arr[j]);
    j++;
}
for(int i=l ; i<=h ; i++)
{
    arr[i]=temp[i-l];
}
}
void me(vector<int>&arr,int l,int h)
{
   
    if(l>h)
    return;
    int mid=(l+h)/2;
    me(arr,l,mid);
    me(arr,mid+1,h);
    merge(arr,l,mid,h);
}
void mergeSort(vector < int > & arr, int n)
{
    me(arr,0,n-1);
}