C++ error 0xC0000005 caused by pointers/dynamic allocation

I'm trying to implement MergeSort using pointers , and everything works until i call the function multiple times in a row , then the code breaks and returns this error 0xC0000005 . I'm assuming it's due to memory getting full since i'm not deallocating it. I'm new to dynamic memory and pointers and don't really know how to fix it.

int* MergeV1(int *x,int n,int *y,int m)
{
    int i=1,j=1,l=0;
    int *aux=new int[n+m+1];
    while(i<=n&&j<=m)
    {
        while(i<=n&&x[i]<=y[j])
            aux[++l]=x[i++];
        while(j<=m&&y[j]<=x[i])
            aux[++l]=y[j++];
    }
    while(i<=n)
        aux[++l]=x[i++];
    while(j<=m)
        aux[++l]=y[j++];
    return aux;

}
int* MergeSortV1(int* v,int n)
{
    if(n==1)
        return v;
    int m=n/2;
    int lenst=m;
    int lendr=m;
    if(n%2)
        lendr++;
    int *s,*d;
    s=MergeSortV1(v,lenst);
    d=MergeSortV1(&v[m],lendr);
    return MergeV1(s,lenst,d,lendr);
}