#ifndef KHOA
#include "gap.h"
#endif // KHOA
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld double
#define FOR(i,l,r) for(int i = (l), _r = (r); i <= _r; i++)
#define FORNG(i,r,l) for(int i = (r), _l = (l); i >= _l; i--)
#define REP(i,r) for(int i = 0, _r = (r); i < _r; i++)
#define endl '\n'
#define fi first
#define se second
#define pb push_back
#define all(v) (v).begin(),(v).end()
#define size(v) ((ll)(v).size())
#define MASK(x) (1LL << (x))
#define BIT(x, i) (((x) >> (i)) & 1)
const ll MOD = 1e9 + 7, N = 2e5 + 10, INF = 2e18, LOG = 21;
ll a[N];
#ifdef KHOA
ll A[N] = {-2008, };
void MinMax(ll x,ll y,ll *z,ll *t){
bool ok = 0;
FOR(i,1,10){
if(x <= a[i] && !ok){
*z = a[i];
ok = 1;
}
if(a[i] <= y)*t = a[i];
}
}
#endif
ll findGap(int T, int n){
ll L = 0, R = 1e18;
ll lo, hi;
MinMax(L, R, &lo, &hi);
L = lo, R = hi;
ll sz = (R - L + n - 1) / (n - 1);
ll last = L, ans = -INF;
ll i;
for(i = lo + 1; i + sz < R; i += sz){
MinMax(i, i + sz, &lo, &hi);
if(lo != -1){
ans = max(ans, lo - last);
last = hi;
}
}
if(lo != -1)ans = max(ans, R - last);
return ans;
}
#ifdef KHOA
int main(){
FOR(i,1,10)a[i] = i * 10,cerr<<a[i]<<' ';
cerr<<endl;
cout<<findGap(1, 10);
}
#endif
