#include <iostream>

using namespace std;
//autor: Kacper Warot

float ILORAZ (float a, float b)
{
    if (b==0)
        return -1;
    else
        return a/b;
}
int main()
{
    int a,b;
    cin >> a >> b;
    cout << ILORAZ(a,b);
    return 0;
}