N=int(input())
ans=0
for _ in range(N):
    L=list(input().split("."))
    if len(L)==1:
        L.append("0")
    b=1
    if L[0][0]=="-":
        b=-1
        L[0]=L[0][1:]
    while len(L[1])<10:
        L[1]+="0"
    for i in range(2):
        L[i]=int(L[i])*b
    ans+=L[0]*10000000000
    ans+=L[1]
ans=str(ans)
print(ans[:len(ans)-10]+"."+ans[len(ans)-10:])