ntheven

#include <iostream>
#define N 201
using namespace std;
typedef int Huge[N];

void AtribValue(Huge H,unsigned long long int X)
{
    H[0] = 0;
    while(X)
        ++H[0],H[H[0]]=X%10,X/=10;
}

void Mult(Huge H,int X) /// H <- H*X
{
    int T=0;
    for(int i=1;i<=H[0];++i)
        H[i]=H[i]*X+T,T=H[i]/10,H[i]=H[i]%10;
    while (T) /// Cat timp exista transport
        H[++H[0]]=T%10,T/=10;
}

void Afis(Huge A)
{
    for(int i=A[0];i>0;--i)
        cout<<A[i];
    cout<<'\n';
}

int main()
{
    unsigned long long int n;
    cin>>n;
    Huge A;
    AtribValue(A,n);
    Mult(A,2);
    Afis(A);
    return 0;
}