What will happens if the statement free(a) is removed in the following C code?

#include<stdio.h>
#include<stdlib.h>
main()
{
    int *a;
    a=(int*)malloc(sizeof(int));
    *a=100;
    printf("*a%d",*a);
    free(a);
    a=(int*)malloc(sizeof(int));
    *a=200;
    printf("a%p",a);
    *a=200;
    printf("a%d",*a);
}