Ошибка сегментирования. Си сортировка

Опять поймала ошибку сегментирования, не могу понять, что я делаю не так. GDB пробовала пройтись, вылетает в мэйне и не могу понять, почему.

    #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <time.h>
#include "Sorts.h"

int main(void)
{    clock_t start, end;
     double cpu_time_used;
    int size=100;
    FILE *unsort = NULL;
        FILE *sort = NULL;
    FILE *sort2=NULL;
    int *number1 = (int) malloc (size*sizeof(int));
    int number;
 
    unsort = fopen("Unsort.txt", "w");  
    

    if (unsort == NULL) {
        printf("Error opening file");
    return -1;
    }
   
 
    
    for (int i = 0; i<size;i++){
    number = generate_number();
    fwrite(&number, sizeof(int), 1, unsort);
    }
   
    fclose(unsort);
        

sort = fopen("sorted.txt", "w");
if (sort == NULL) {
        printf("Error opening file");
    return -1;
        }
unsort = fopen("Unsort.txt", "r");


for(int i = 0; i < size; i++)
    {
    
       fscanf(unsort,"%d",number1[i]);  
        
}
        start = clock();
        ShellSort(number1, size);
    end = clock();
     cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;

        fprintf( stderr, "CPU time used for ShellSort = %lf\n", cpu_time_used );
for(int i = 0; i < size; i++)
    {
     fprintf(sort, "%d", number1[i]);

    }
fclose(sort);
number1 = (int) realloc (size,sizeof(int));
sort2 = fopen("sort2.txt", "w");
 if (sort2 == NULL) {
        printf("Error opening file");
    return -1;
        }
for(int i = 0; i < size; i++)
    {
    
    
         fscanf(unsort,"%d",number1[i]);
}

    start = clock();
         MergeSort(number1, size);
    end = clock();
     cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;

        fprintf( stderr, "CPU time used for MergeSort = %lf\n", cpu_time_used );
for(int i = 0; i < size; i++)
    {
    fprintf(sort2, "%d", number1[i]);

    }           
fclose(unsort);
free(number);

fclose(sort2);

    return 0;
}

библиотека нормально подключается и работает, вроде.

  #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <stddef.h>
#include <stdint.h>

int generate_number()
{
    srand(time(NULL));

   int R=rand() % 100 - 50 ;
    return R;
}


void ShellSort(int n, int *mass[])
{
    int i, j, step;
    int tmp;
    for (step = n / 2; step > 0; step /= 2)
        for (i = step; i < n; i++)
        {
            tmp = mass[i];
            for (j = i; j >= step; j -= step)
            {
                if (tmp < mass[j - step])
                    mass[j] = mass[j - step];
                else
                    break;
            }
            mass[j] = tmp;
        }
}


void MergeSort(int n, int *mass[])
{
  int mid = n / 2; 
  if (n % 2 == 1)
    mid++;
  int h = 1; 
  int *c = (int*)malloc(n * sizeof(int));
  int step;
  while (h < n) 
  {
    step = h;
    int i = 0;   
    int j = mid; 
    int k = 0;   
    while (step <= mid) 
    {
      while ((i < step) && (j < n) && (j < (mid + step))) 
      { 
        if (mass[i] < mass[j])  
        {
          c[k] = mass[i];
          i++; k++;
        }
        else {
          c[k] = mass[j];
          j++; k++;
        }
      }
      while (i < step) 
      { 
        c[k] = mass[i];
        i++; k++;
      }
      while ((j < (mid + step)) && (j<n)) 
      { 
        c[k] = mass[j];
        j++; k++;
      }
      step = step + h; 
    }
    h = h * 2;
    
    for (i = 0; i<n; i++)
      mass[i] = c[i];
  }