Segmentation fault (core dumped) only bigger input

My code works perfectly if the seive(n) is 1000000. If seive(n) is more than 10000000, it shows me segmentation fault (core dumped).I've read about segmentation fault. But i couldn't solve with that.

    #include <stdio.h>    #include <math.h>    using namespace std;    int seive(long int n)    {        long int A[n];        for (long int i = 2; i <= n; i += 1)        {            A[i] = i;        }        long int root = (int)sqrt(n);        for(int j = 2; j <= root; j++)        {            for(int k = 2*j; k < n ; k = k + j)            {                       A[k] = 0;            }        }        int count = 0;        for (int l = 2; l < n; ++l)        {            if(A[l] != 0) count++;        }        printf("%d\n", count);    }    int main()    {        seive( 1000000);    }