Deleting digits

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

ll f_maxdigi(ll n)
{
    ll ans = -1;
    while(n)
    {
        ans = max(ans, n % 10);
        n /= 10;
    }
    return ans;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);

    ll n, ans = 0;
    cin >> n;
    while(n)
    {
        n -= f_maxdigi(n);
        ans++;
    }
    cout << ans;

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED