#include <stdio.h>
int main(){
	int n;
	int i;
	int r;
	int max;
	printf("Enter a Number\n");
	scanf("%d",&n);
	max=n%10;
	for (i = n;i > 0;i = i / 10){
		r=i%10;
		if (r > max){
			max=r;
		}
	}
	printf("%d\n",max);
	return 0;
}