/*
TASK:minitime
LANG:C++
*/
#include <iostream>
#include <math.h>
using namespace std;
int main()
{
    int a[110],n;
    double l;
    cin>>n;
    for (int i=1;i<=n;i++) if ((i*i>=n) && (i*i-2*i-1<n)) { l=i;break;}
    if ((n>4)&& (n<=l*l)) cout<<2*l<<endl;
    if (n<=4) cout<<n<<endl;
    if ((n>4) && (n>l*l)) cout<<2*l+1<<endl;
    return 0;
}
