#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;
}

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