is there some sort of memory limit in the solutions we submit..is it okay to use unsigned long long arr[10^7] or does it give sigsegv??

i have this code for TSORT...it works fine on my computer but gives run time error SIGSEGV ..pls have a look at it and tell me whats the bug...thanks...

#include<stdio.h>

void partition(unsigned long long arr[],unsigned long long first,unsigned long last);
void m_sort(unsigned long long arr[],unsigned long long low,unsigned long long mid,unsigned long long high);

int main(void)
{
    unsigned long long t,n,i=0;
    unsigned long long arr[10^7];
    scanf("%llu",&n);
    t=n;
    //accepting elements
    while(t--)
    {
        scanf("%llu",&arr[i++]);
    }
    partition(arr,0,n-1);

    for(i=0;i<n;i++)
        printf("%llu\n",arr[i]);
    return 0;
}
void partition(unsigned long long arr[],unsigned long long first,unsigned long last)
{
    unsigned long long mid;
    if(first<last)
    {
      mid=(first+last)/2;
      partition(arr,first,mid);
      partition(arr,mid+1,last);
      m_sort(arr,first,mid,last);
    }
}
void m_sort(unsigned long long arr[],unsigned long long low,unsigned long long mid,unsigned long long high)
{
    unsigned long long temp[10^7];
    unsigned long long k=low;
    unsigned long long i=low;
    unsigned long long m=mid+1;
    while(i<=mid&&m<=high)
    {
        if(arr[i]<=arr[m])
        {
            temp[k++]=arr[i++];
        }
        else
        {
            temp[k++]=arr[m++];
        }
    }
    if(i>mid)
    {
        while(m<=high)
        {
            temp[k++]=arr[m++];
        }
    }
    else
    {
        while(i<=mid)
        {
            temp[k++]=arr[i++];
        }
    }
    for(i=low;i<=high;i++)
    {
        arr[i]=temp[i];
    }
}