/*   /\_/\
    (= ._.)
    / >0  \>1
*/
#include <bits/stdc++.h>

using namespace std;


typedef long long ll;
const int nmax = int(1e6) + 10;

vector<ll> c;
ll n;
int main() {
    //freopen(".inp" , "r" , stdin);
    //freopen(".out" , "w" , stdout);

    ios::sync_with_stdio(false);
    cin.tie(0);

    cin >> n;
    for (ll i = 1; i <= 9; ++i)
    {
        ll z = i;
        for (ll j = 1; j <= 16; ++j)
        {
            c . push_back(z);
            z = z * 10 + i;
        }
    }
    sort (c . begin(), c . end());
    ll l = 0, r = c . size() - 1, ans = 0;
    while (l <= r)
    {
        ll mid = (l + r) / 2;
        if (c[mid] > n)
        {
            ans = c[mid];
            r = mid - 1;
        }
        else
        {
            l = mid + 1;
        }
    }
    cout << ans - n;
    return 0;
}

/*
đố bt con gì 
 /\_/\  
( o.o ) 
 > - <
 
 */
#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll ham(ll n,ll dem)
{
    ll t=0;
    while(dem>0)
    {
        t=t*10+n;
        dem--;
    }
    return t;
}
int main()
{
    ll n;
    cin>>n;
    ll max1=0;
    ll dem=0;
    ll t=n;
    while(n>0)
    {
        max1=max(max1,n%10);
        dem++;
        n/=10;
    }
    if(ham(max1,dem)-t==0)
    {
        cout<<ham((ll)1,dem+1)-t;
    }
    else cout<<ham(max1,dem)-t;
}