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