#include<stdio.h>
int main()
{
 int a,b,n;
 scanf("%d",&n);
 a=10;
 while(n!=0)
 {
  b=n%10;
  
  if(a>b)
  
  a=b;
  n=n/10;
 }
 printf("%d",a);
 return 0;
}