#include<bits/stdc++.h>
using namespace std;
signed main(){
	int a;
	cin>>a;
	cout<<a*4;
}

玩个好玩的：

a=int(input())
print(a*4)

答案就是 $n\times4$。

#include<bits/stdc++.h>
#define int long long
#define INF 0x3f3f3f
using namespace std;
int n;
signed main(){
	cin>>n;
	cout<<n*4;
	return 0;
}