import sys

sys.setrecursionlimit(10**7)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


N = I()
ans = 0
for _ in range(N):
    A = S()
    if '.' in A:
        for i in range(100):
            if A[i] == '.':
                index = i
                break
        X = abs(int(A[:index]))
        Y = int(A[index+1:])*10**(10-(len(A)-index-1))
        if A[0] == '-':
            ans -= X*10**10+Y
        else:
            ans += X*10**10+Y
    else:
        ans += int(A)*10**10

if ans >= 0:
    q,r = divmod(ans,10**10)
    r = '0'*(10-len(str(r)))+str(r)
    print(str(q)+'.'+r)
else:
    ans = abs(ans)
    q,r = divmod(ans,10**10)
    r = '0'*(10-len(str(r)))+str(r)
    print('-'+str(q)+'.'+r)