#include<iostream> #include<cstdio> //scanf()\printf() #include<cstring> #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int s=1,n=1,m; cin>>m; while(s<=m){ n++; s*=n; } cout<<n; return 0; }