20分-

#include<bits/stdc++.h>
using namespace std;
long double ans,s;
int main(){
	while(scanf("%lf",&s)!=-1){
		ans+=s*1000000;
	} 
	printf("%.5lf",ans/1000000);
	return 0;
}

ac代码

#include<bits/stdc++.h>
using namespace std;
long double ans,s;
int main(){
	while(scanf("%LF",&s)!=-1){
		ans+=s*1000000;
	} 
	printf("%.5LF",ans/1000000);
	return 0;
}