#include <bits/stdc++.h>
#define przxct ""
#define fto(i,j,h)    for (int i=j; i<=h; ++i)
#define maxn
#define ll long long
#define pi 3.141592653589

using namespace std;

string x;
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    cin >> x;
    string rs = "";
    fto(i,0,x.length()-1)
    {
        if (x[i] == '.')    break;
        rs += x[i];
    }
    cout << rs;
    return 0;
}

#include <bits/stdc++.h>
typedef long long ll;
#define rep(i, n) for(long long i = 0; i < (long long)(n); i++)
#define rep1(i, n) for(long long i = 1; i <= (long long)(n); i++)
#define INF 1000000000000 //10^12:∞
#define MOD 1000000007

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
 
int main() {
	cin.tie(0);
   	ios::sync_with_stdio(false);
    ll n,saidai,m;
    ll stop = 0;
    cin >> n;
    saidai = n+1;
    m = saidai/2+1;
    rep1(i,m){
        if(saidai-i>=0){
            saidai = saidai-i;
            stop++;
        }else{
            break;
        }
    }
    cout << n-stop+1;
}