DIU_TC_01 D

#include<bits/stdc++.h>

using namespace std;

///Template
#define in1()   freopen("E:\\Random Programs\\template\\test_input.txt", "r", stdin)
#define out1()  freopen("E:\\Random Programs\\template\\test_output.txt", "w", stdout)
#define in2(f)  freopen("f", "r", stdin)
#define out2(f) freopen("f", "w", stdout)

//Datatypes
#define l       long
#define ll      long long
#define llu     unsigned long long

//loop
#define f1(i,x,y)   for(int i=x;i<=y;i++)

//Constants
#define MAX     10000007
#define PI      acos(-1.0)

int main()
{
//  in1();
//  out1();
    double a, b;
    cin>>a>>b;

    a=a+1e-15;
    b=b+1e-15;

    ll x=a*1000000000;
    ll y=b*1000000000;
    ll rem=x%y;

    double d=rem/(1000000000*1.0);

    printf("%0.9lf\n", d);

    return 0;
}