C program to find the maximum value from array using function

Write a program which should consists of a user defined function "maximum()". Pass 1D array to the function, along with number of elements of array. Find out the maximum element in 1D array using this function. 

 #include<stdio.h>
 int maximum(int*,int);
 int main()
 {
 	int num[100],n,a,max;	;
 	printf("How many element you want to store : "); 
 	scanf("%d",&n);
 	for(a=0;a<n;a++)
 	{
 		scanf("%d",&num[a]);
	}
	max=maximum(num,n);
	printf("The Maximum Element of array is: %d",max);
	return 0;
 }
 int maximum(int *ptr,int n)
 {
 	int a,max;
 	max=*ptr;
 	for(a=1;a<=n;a++)
 	{
 		if(max<*ptr)
		{
            max=*ptr;
        }
        ptr++;
	}
	
	return(max);
 }

How many element you want to store : 5

3

4

5

66

3

The Maximuim Element of array is: 66