E. Area of a Circle – Codeforces Problem Solution in C++

Disclaimer: Make sure you tried enough before checking the solution

Problem: https://codeforces.com/group/MWSDmqGsZm/contest/219158/problem/E

#include<bits/stdc++.h>
using namespace std;
int main()
{
	double PI = 3.141592653;
	double r;
	cin>>r;
	cout<<fixed << setprecision(9)<<PI * r * r<<endl;
	
}

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