#include<stdio.h>
int main()
{
	int a,b,i,max=0;
	printf("please enter the number\n");
	scanf("%d", &a);

	while (a != 0)
	{
		b = a%10;
		if (b > max)
			max = b;
		a = a/10;
	}

	printf("%d", max);
	printf("\n");
	return 0;
}