#include <bits/stdc++.h>   using namespace std;   int n;   double a[4010];   int main() {     cin >> n;     n *= 2;     for (int i = 1; i <= n; ++i) cin >> a[i];     for (int i = 1; i <= n; ++i) a[i] = a[i] - int(a[i]);     int cnt = 0;     for (int i = 1; i <= n; ++i)       if (abs(a[i] - 0) <= 0.0000001) cnt++;     double sum = 0;     for (int i = 1; i <= n; ++i) sum += a[i];     double res = 1000000001;     for (int i = 0; i <= cnt; ++i) res = min(res, abs(n / 2 - sum - i));     printf( %.3f , res);   }   