Exception thrown at 0x00007FF6021F251F in openmp.exe: 0xC0000005: Access violation reading location 0x00000000000000F0. in open-mp

I'm trying to use a parallel code in c++ program using open-MP. this Code without openmp runs well. I see this crash in line 65 and 66 when parallel code is solved .

Exception thrown at 0x00007FF6021F251F in openmp.exe: 0xC0000005: Access violation reading location 0x0000000000000000.

my code is:

#include <stdio.h>
#include <iostream>
#include <omp.h>
#include <math.h>
#include <Windows.h>
using namespace std;

int i, j, m;
double**** g, **** f;
int n = 50;
LARGE_INTEGER StartingTime, EndingTime, ElapsedMicroseconds;
LARGE_INTEGER Frequency;
int main()
{
    QueryPerformanceFrequency(&Frequency);
    QueryPerformanceCounter(&StartingTime);

    f = new double*** [n];
    g = new double*** [n];
    


    for (int i = 0; i < n; i++)
    {
        f[i] = new double** [n];
        g[i] = new double** [n];

        for (int j = 0; j < n; j++)
        {

            f[i][j] = new double* [n];
            g[i][j] = new double* [n];
            

            for (int k = 0; k < n; k++)
            {
                f[i][j][k] = new double[n];
                g[i][j][k] = new double[n];
            }

        }

    }

# pragma omp parallel
    {

        m = omp_get_num_procs();
        printf("number of processor= %d \n", m);
        m = omp_in_parallel();
        printf("if program in paralle=1 or serial=0 ?? %d \n", m);
        m = omp_get_max_threads();
        printf("muaximum number of thread= %d \n", m);
        m = omp_get_num_threads();
        printf("number of threads= %d \n", m);
        m = omp_get_thread_num();
        printf("thread number is= %d \n", m);

#pragma omp for schedule (static,10)
for(i=0 ; i <n ;i++)
    for (j = 0; j < n; j++)
        for(int k=0;k<n;k++)
            for(int a=0;a<n;a++)
        {
        f[i][j][a][k] = 1;
        g[i][j][a][k] = 2;
        }

    }

    QueryPerformanceCounter(&EndingTime);
    ElapsedMicroseconds.QuadPart = EndingTime.QuadPart - StartingTime.QuadPart;
    ElapsedMicroseconds.QuadPart *= 1000000000;
    ElapsedMicroseconds.QuadPart /= Frequency.QuadPart;
    cout << "time : " << ElapsedMicroseconds.QuadPart << endl;

}

Can you help me solve the problem?