include<iostream>

using namespace std; int main() { int a,b,c; cin>>c; a=1; b=1; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++; if(a+b<=c+1) b++;
cout<<(b); return 0; }