#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main() {
    int x;
    double precision = 1e-5;
    
    printf("***輸入x值(x>0)計算平方根***\n");
    
    // 清空輸入緩衝區
    int c;
    while ((c = getchar()) != '\n' && c != EOF);
    
    // 使用 fgets 和 sscanf 來讀取輸入
    char input[100];
    if (fgets(input, sizeof(input), stdin) == NULL) {
        printf("讀取輸入時發生錯誤\n");
        return 1;
    }
    
    if (sscanf(input, "%d", &x) != 1 || x <= 0) {
        printf("無效的輸入。請輸入一個正整數。\n");
        return 1;
    }

    int lower = 0, upper = x;
    double ans = sqrt(x);
    double mid;

    while (upper - lower > precision) {
        mid = (lower + upper) / 2.0;
        if (mid * mid > x) {
            upper = mid;
        } else {
            lower = mid;
        }
    }
    
    printf("%d的平方根為%f\n", x, mid);
    printf("sqrt(%d)的結果為%f\n", x, ans);

    return 0;
}