#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll factorial(ll n) {
if (n <= 1) {
return 1;
}
ll result = 1;
for (ll i = 1; i <= n; i++) {
result *= i;
}
return result;
}
ll digitcount(ll n) {
if (n <= 1) {
return 1;
}
ll temp = n/10;
return digitcount(temp)+1;
}
int main() {
int R;
cin>>R;
ll n = factorial(R);
n= digitcount(n);
cout<<"Number of digits of "+to_string(R)+"! is "+to_string(n)<<endl;
return 0;
}
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