1 #include <iostream>
2 #define _for(i,a,b) for(int i = (a);i < b;i ++)
3 #define _rep(i,a,b) for(int i = (a);i > b;i --)
4 #define INF 0x3f3f3f3f
5 #define MOD 1000000007
6 #define maxn 50003
7 typedef long long ll;
8
9 using namespace std;
10 typedef pair<int,int> P;//first 是最短距离，second 是顶点编号
11 inline ll read()
12 {
13 ll ans = 0;
14 char ch = getchar(), last = ' ';
15 while(!isdigit(ch)) last = ch, ch = getchar();
16 while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();
17 if(last == '-') ans = -ans;
18 return ans;
19 }
20 inline void write(ll x)
21 {
22 if(x < 0) x = -x, putchar('-');
23 if(x >= 10) write(x / 10);
24 putchar(x % 10 + '0');
25 }
26 long double rnt = 0.0;
27 long double a;
28 int main()
29 {
30 // freopen("testdata (2).in","r+",stdin);
31 while(~scanf("%Lf",&a))
32 rnt += a*1000000;
33 printf("%.5Lf",rnt/1000000);
34 return 0;
35 }
