#include <stdio.h>
int main()
{
int N, cnt = 0, i, res = 0, one=0;
int arr[3] = {};
scanf_s("%d", &N);
if (N < 10)
{
arr[0] = 0;
arr[1] = N;
}
else if (N >= 10 && N < 100)
{
arr[0] = N / 10;
arr[1] = N % 10;
}
while (1)
{
res = arr[0] + arr[1];
one = arr[1]*10;
if (res < 10)
{
arr[0] = 0;
arr[1] = res;
}
else if (res >= 10 && res < 100)
{
arr[0] = res / 10;
arr[1] = res % 10;
}
res = one + arr[1];
cnt++;
if (res == N)
{
printf("%d", cnt);
break;
}
if (res < 10)
{
arr[0] = 0;
arr[1] = res;
}
else if (res >= 10 && res < 100)
{
arr[0] = res / 10;
arr[1] = res % 10;
}
}
return 0;
}