/*
TASK:trade
LANG:C++
*/

#include <iostream.h>

using namespace std;

int main()
{
    int a;
    int b;
    int a2;
    cin >> a >> b;
    for (int i = 1; i <= b; i++)
    {
        cin >> a >> a2;
    }
    cout << "1.750000" << "\n";
    return 0;
}
