Segmentation fault 11 (probably in struct) before the main functin even started

I'd like to know where is the mistake in my code. I just started learning C and I just got to pointers and arrays so I have no idea where the mistake is. The problem seems to be in the part where I use struct to create my own data type because none of the debug texts that I've put in show themselves in console when I run the program. I've looked on the internet for an answer but haven t found anything. Any help would be appreciated.

#include <stdio.h>

#include <stdlib.h>

#define MAX_size 2000

typedef struct TMatrix{

    int grid[MAX_size][MAX_size];

    int sizex;

    int sizey;

} TMATRIX;

int readSize(TMATRIX *matrix);



int main(void){

    TMATRIX matrix;

    printf("DEBUG\n");

    if (readSize(&matrix)==1){

        printf ("Invalid input.\n");

        return 1;

    }



    printf("%d %d\n", matrix.sizex,matrix.sizey);



    return 0;

}



int readSize(TMATRIX *matrix){

    printf("DEBUG\n");

    if (scanf("%d %d", &matrix->sizex, &matrix->sizey)!=2) return 1;

    if (matrix->sizex<1 || matrix->sizey<1) return 1;



    return 0;

}