Untitled

#include <bits/stdc++.h>
#define endl '\n'
#define maxn 105
#define TASK bai1
#define For(i,a,b) for ( int i = a; i <= b; i++ )
#define Ford(i,a,b) for ( int i = a; i >= b; i-- )
#define MOD 100000000000007

using namespace std;
int d = 0,n;
int Sum(int x)
{
    int res = 0;
    while(x > 0)
    {
        res += x % 10;
        x /= 10;
    }
    return res;
}
void inp()
{
    cin >> n;
}
void solve()
{
    while(d <= 81)
    {
        d++;
        if(Sum(n - d) + n - d == n) break;
    }
    cout << n - d;
}
int main()
{
    ios_base:: sync_with_stdio(0);
    cin.tie(0);
    if(fopen("bai1.inp","r")){
        freopen("bai1.inp","r",stdin);
    }
    inp();
    solve();
}