#include<bits/stdc++.h>
using namespace std;
int main(){
	float e,c;
	int a,d;
	scanf("%d",&a);
	d=a%10;
	c=a/10%10;
	e=c/d*1.0;
	printf("%.1f",e);
}
/**************************************************************
	Problem: 1607
	User: tonghuawei
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2076 kb
****************************************************************/