Implementation of Merge Sort in C

The following code shows an Implementation of Merge Sort in C Language.

// Implementation of Merge Sort in C

#include <stdio.h>
void Merge(int myarray[], int first, int last, int middle);
void MergeSort(int myarray[], int first, int last)
{
    int middle;
    if(first<last)
    {
        middle=(first+last)/2;
        MergeSort(myarray, first, middle);
        MergeSort(myarray, middle+1, last);
        Merge(myarray, first, last, middle);
    }
    else
    {
        return;
    }
}
void Merge(int myarray[], int first, int last, int middle)
{
    int size1, size2, i, i1, i2, i3;
    size1=1+middle-first;
    size2=last-middle;
    
    int first_array[size1], second_array[size2];
    for(i=0;i<size1;i++)
    {
        first_array[i]=myarray[first+i];
    }
    for(i=0;i<size2;i++)
    {
        second_array[i]=myarray[1+i+middle];
    }
    i1=i2=0;
    i3=first;
    
    while((i1<size1) && (i2<size2))
    {
        if(first_array[i1]<second_array[i2])
        {
            myarray[i3]=first_array[i1];
            i1++;
        }
        else
        {
            myarray[i3]=second_array[i2];
            i2++;
        }
        i3++;
    }
    while(i1<size1)
    {
        myarray[i3]=first_array[i1];
        i1++;
        i3++;
    }
    while(i2<size2)
    {
        myarray[i3]=second_array[i2];
        i2++;
        i3++;
    }
}
int main()
{
    int i, j, elements_count;
    int myarray[]={8, 12, -9, 30, 29, -80, 55, 62, 83, 44, -12, 6, 15};
    elements_count=sizeof(myarray)/sizeof(int);
    printf("Original Array....\n");
    for(i=0;i<elements_count;i++)
        printf("%d ", myarray[i]);
    printf("\n\n");
    MergeSort(myarray, 0, elements_count);
    printf("Sorted Array....\n");
    for(i=0;i<elements_count;i++)
        printf("%d ", myarray[i]);
    printf("\n\n");
    return 0;
}

Output

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