C Program for Memory Allocation and Reallocation

/*
Write a program to store a character string in a block of memory space created by malloc and then modify the same to store a large string.
*/

#include <stdio.h>
#include <stdlib.h>

int main(void) 
{
char *ch;
int n,n1;
printf("\n Enter Size of String you Want : ");
scanf("%d",&n);

if((ch = (char *)malloc(n *sizeof(char))) == 0)
        {
            printf("\n No space available");
            exit(1);
        }
    else
      {
          printf("\n %ld Bytes Space are allocated Successfully", n * sizeof(char));
      }

    printf("\nEnter String :");
    scanf("%s",ch);

    printf("\n String is : %s",ch);

    printf("\n Enter Size You Want Increase: ");
    scanf("%d",&n1);
   
if((ch = (char *)realloc(ch,(n+n1) *sizeof(char))) == 0)
        {
            printf("\n No extra space available");
            exit(1);
        }
    else
      {
          printf("\n %ld Bytes Space are allocated Successfully", (n+n1) * sizeof(char));
      }
    
printf("\nEnter New String :");
    scanf("%s",ch);
    printf("\n New String is : %s",ch);

    return 0;
}