#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
int INF = 1e9;
int MOD = 1000000007;
ll pow(int n){
    ll ans = 1;
    for(int i = 0;i < n;i++){
        ans *= 10;
    }
    return ans;
}
main(){
    int N;
    ll usum = 0,dsum = 0;
    cin >> N;
    for(int i = 0;i < N;i++){
        int nflag = 1;
        ll a,b = 0;
        string s;
        cin >> s;
        if(s[0] == '-'){
            nflag = -1;
            s.erase(s.begin());
        }
        int index = s.find(".");
        if(index != -1){
            a = stoll(s.substr(0,index));
            b = stoll(s.substr(index+1,s.length()-index-1));
            b *= pow(11-s.length()+index);
        }else a = stoll(s);
        usum += a * nflag;
        dsum += b * nflag;
    }
    if(usum == 0){
        printf("%s0.%010lld\n",signbit(dsum)?"-":"",llabs(dsum));
        return 0;
    }else if(signbit(usum) == signbit(dsum)){
        usum += dsum / pow(10);
        dsum %= pow(10);
    }else{
        usum -= dsum / pow(10);
        usum += signbit(usum)*2 - 1;
        dsum %= pow(10);
        dsum = pow(10) - dsum*(1 - signbit(dsum)*2);
    }
    printf("%lld.%010lld\n",usum,dsum);
}