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

using i8 = int8_t;
using i16 = int16_t;
using i32 = int32_t;
using i64 = int64_t;
using isize = ptrdiff_t;
using u8 = uint8_t;
using u16 = uint16_t;
using u32 = uint32_t;
using u64 = uint64_t;
using usize = size_t;
using f32 = float_t;
using f64 = double_t;

inline constexpr i32 Modulus = 1e9 + 7;

template <typename TScalar, typename... TRest>
inline constexpr TScalar Min(TScalar first, TRest... rest)
{
    static_assert((is_same_v<TScalar, TRest> && ...), "All arguments must have the same type");
    if constexpr (sizeof...(rest) == 0)
        return first;
    else
        return (first < Min(rest...)) ? first : Min(rest...);
}

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

    u32 n;
    cin >> n;

    constexpr u32 MaxSteps = 1e6 + 17;
    vector<u32> dp(n + 1, MaxSteps);
    dp[n] = 0;

    for (u32 num = n; num > 0; num -= 1)
    {
        if (dp[num] == MaxSteps)
        {
            continue;
        }

        u32 clone = num;
        while (clone > 0)
        {
            u32 digit = clone % 10;
            clone /= 10;
            dp[num - digit] = Min(dp[num - digit], 1 + dp[num]);
        }
    }

    cout << dp[0];

    return 0;
}