#include <stdio.h>
int sqrt(int n){
    if (n == 0) return 0;
    if (n == 1) return 1;
    int x=n;
    int x_b;
    do{
        x_b=x;
        x=(x_b+n/x_b)/2;
        if (x <= n / x && (x + 1) > n / (x + 1)) 
            break;
    
}while(x!=x_b);return x;}
int main() {
   int n;
   scanf("%d",&n);
   printf("%d\n",sqrt(n));
    return 0;
}