20250701
#include <stdio.h>
#include <stdlib.h>
// 10 9 8 7 6 5 4 3 2 1
int main() {
int arr[9999] ={0}, v=0, n,k;
int cnt = 0, temp,i, nowIndex=0;
scanf("%d", &n);
temp = n;
i=0;
while (temp!=0) {
arr[i] = temp%10;
temp/=10;
cnt++;
i++;
}
for (i=n-1; i>0; i--) {
nowIndex = 0;
v=0;
for (int j=0; j<=cnt; j++) {
v += arr[nowIndex] * i;
if (v>=10) {
arr[nowIndex] = v%10;
v = v/10;
}
else {
arr[nowIndex] = v;
v=0;
}
nowIndex++;
}
arr[nowIndex] = v;
if (v>0) {
cnt++;
}
}
k=0;
while ((int)arr[k]==0) {
k++;
}
if (n==0) {
printf("0");
}
else {
printf("%d",k);
}
return 0;
}