Problem:
Score : 100 points

Problem Statement

It is known that the area of a regular dodecagon inscribed in a circle of radius a is 3a^2.

Given an integer r, find the area of a regular dodecagon inscribed in a circle of radius r.

Constraints

1 \leq r \leq 100

r is an integer.

Input

Input is given from Standard Input in the following format:

r

Output

Print an integer representing the area of the regular dodecagon.

Sample Input 1

4

Sample Output 1

48

The area of the regular dodecagon is 3 \times 4^2 = 48.

Sample Input 2

15

Sample Output 2

675

Sample Input 3

80

Sample Output 3

19200

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;

int main(){
    int N, ans =1, M, minNum;
    cin >> N;
    vector<int> a(N), b;
	
    for(int i=0; i<N; i++){
	cin >> a[i];
    }
    
    b.push_back(a[0]);
    minNum= a[0];
    
    for(int i=1; i<N; i++){
	M=b.size();
	    
	for(int j=0; j<M; j++){
	    if(minNum > a[i]){
	    	minNum = a[i];
		ans ++;
		b[ans] = a[i];
		break;	
	    }

	    if(b[j] < a[i]){
		b[j] = a[i];
		if(j == M-1)
		    minNum = a[i];
		break;
	    }
	    else if(j==M-1){
		minNum = a[i];
		ans ++;
		b.push_back(a[i]);
		sort(b.begin(), b.end());
	    }
	}
    }
    cout << ans << endl;
}