D

#include<bits/stdc++.h>
using namespace std;
int main(){
	double a,b;
	long long c;
	cin>>a>>b;
	b/=10;
	c=a*b;
	c+=5;
	c/=10;
	c*=10;
	cout<<c; 
}

E

#include <iostream>
using namespace std;

int main() {
    long long a, b, c;  // 使用long long防止大数溢出
    cin >> a >> b >> c;
    
    long long result = 2 * (a * b + a * c + b * c);
    cout << result << endl;
    
    return 0;
}

F

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int a,b,c,max=0;
	cin>>a>>b>>c;
	if(a>max)
	{
		max=a;
	}
	if(b>max)
	{
		max=b;
	}
	if(c>max)
	{
		max=c;
	}
	cout<<max;
}

G

#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    if(n>1&&n<100){
        cout<<"yes"<<endl;
    }
    return 0;
}