1. Write a function that takes as parameter an integer n and returns the largest digit in n.
   Example 1: If n = 3091, your function must return 9
   Example 2: If n = 1385201, your function must return 8
2. Write a main program that asks the user to enter a positive integer number n. Then find and print out the largest digit in n.

#include<stdio.h>

int largest(int n)
{
	int max=0;
	while(n)
	{
		if(n%10>max)
			max=n%10;
		n/=10;
	}
	return max;
}

void main()
{
	int n;
	do{
		printf("Enter a positive integer: ");
		scanf("%d",&n);
	}while(n<0);

	printf("Largest digit in %d is %d\n", n , largest(n));
}