#include <iostream>
#include <map>
#include <string>
#include <vector>
using namespace std;
typedef vector <string> vs;

int main(void){
	map <char, int> m;
	int num[] = {1,5,10,50,100,500,1000};
	for (int i=0; i<7; i++)
		m["IVXLCDM"[i]] = num[i];

	char c;
	string r;
	while (cin>>r){
		int tmp, tmp2= m[r[0]],s=0;
		int n=r.size();
		for (int i=0; i<n; i++){
			tmp = m[r[i]];
			if (tmp2<tmp)
				s-= tmp2*2;
			s += tmp;
			tmp2 = tmp;
		}
		cout<<s<<endl;
	}
}
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#pragma GCC optimize("Ofast")
//*********************************************DO IT NOW****************************************************************
#include<bits/stdc++.h> 
#include<random>
#define int long long   
#define pp pair<int,int> 
#define ss second 
#define ff first 
#define pb push_back
#define mod 1000000007
#define pi 3.14159265359
#define mk(arr,n,type)  type *arr=new type[n];
#define sl s1.length();
#define yes cout<< "YES"<<endl
#define no  cout<< "NO"<<endl
#define all(v) (v).begin(),(v).end()
#define s(v)   sort(v,v+n)
#define  mt mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define read(a,n) for(int i=0;i<n;i++)cin>>a[i]
#define print(a,n) for(int i=0;i<n;i++)cout<<a[i]<<" "
#define for1(i,a,n)  for(int i=0;i<n;i++)
#define rep(i, c) for(int i = 0; i < (int)c; i++)
using namespace std;
//**********************************************DO IT NOW***************************************************************
void fastio()
{  
  #ifndef ONLINE_JUDGE
  freopen("INPUT.txt","r",stdin);
  freopen("OUTPUT.txt","w",stdout); 
  #endif
  ios_base :: sync_with_stdio(false); 
  cin.tie(NULL) ; 
  cout.tie(NULL);
}
int dp[101][1001],ans1=1e9,dp1[1000001];
int num[10];
int a[1000000];
signed main()
{   
    fastio();
    int t=1;
   // cin>>t;
    while(t--)
    { 
        int n;
        cin>>n;
        cout<<2*pi*n;
    }
}
    
// 🍪 🍪 🍪
