#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <queue>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

static const double EPS = 1e-8;
static const double PI = 4.0 * atan(1.0);
static const double PI2 = 8.0 * atan(1.0);

#define REP(i,n)	for(int i=0;i<(int)n;++i)
#define ALL(c)		(c).begin(),(c).end()
#define CLEAR(v)	memset(v,0,sizeof(v))
#define MP(a,b)		make_pair((a),(b))
#define ABS(a)		((a)>0?(a):-(a))
#define FOR(i,s,n)	for(int i=s;i<(int)n;++i)

#define D10 (10000000000)

int main(int argc, char **argv) {
	int N;
	cin >> N;
	ll sum1 = 0, sum2 = 0;
	bool sumsign = true;
	REP(i, N) {
		string A;
		cin >> A;

		int j = 0;
		bool sign = true;
		if (A[0] == '-') {
			sign = false;
			++j;
		}

		ll v1 = 0;
		for (; j < A.length() && A[j] != '.'; ++j) {
			v1 *= 10;
			v1 += A[j] - '0';
		}

		ll v2 = 0;
		REP(k, 10) {
			v2 *= 10;
			v2 += (j + 1 + k < A.size()) ? A[j + 1 + k] - '0' : 0;
		}

		if (v1 == 0 && v2 == 0) sign = true;

		if (sign ^ sumsign) {
			if (v1 == sum1 && v2 == sum2) {
				sign = true;
				sum1 = 0;
				sum2 = 0;
			} else if (v1 > sum1 || (v1 == sum1 && v2 > sum2)) {
				sumsign = sign;
				sum1 = v1 - sum1;
				sum2 = v2 - sum2;
				if (sum2 < 0) {
					sum2 += D10;
					sum1 -= 1;
				}
			}
			else {
				sum1 -= v1;
				sum2 -= v2;
				if (sum2 < 0) {
					sum2 += D10;
					sum1 -= 1;
				}
			}
		}
		else {
			sum1 += v1;
			sum2 += v2;
			if (sum2 >= D10) {
				sum2 -= D10;
				sum1 += 1;
			}
		}
	}
	if (!sumsign) cout << "-";
	cout << sum1 << "." << setw(10) << setfill('0') << sum2 << endl;
	return 0;
}