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