#include<stdio.h>

void find_divider(int n)
{
    const inf=-1e9;
    int divider,remainder_max=inf;
    for(int i=1;i<=200;i++){
        remainder=n%i;
        if(remainder>remiander_max){
            remainder_max=remainder;
            divider=i;
        }
    }
    printf("%d",divider);
}

int main()
{
    int n;
    scanf("%d",&n);
    find_divider(n);
    return 0;
}