Problem:
Score : 200 points

Problem Statement

Find the largest square number not exceeding N. Here, a square number is an integer that can be represented as the square of an integer.

Constraints

1 \leq N \leq 10^9

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the largest square number not exceeding N.

Sample Input 1

10

Sample Output 1

9

10 is not square, but 9 = 3 × 3 is. Thus, we print 9.

Sample Input 2

81

Sample Output 2

81

Sample Input 3

271828182

Sample Output 3

271821169

Solution in C (GCC 5.4.1) (judge verdict: Accepted)

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

void ToiB(void);

int main(void)
{   
    ToiB();
    return 0;
}

void ToiB(void){
    int N; scanf("%d", &N);
    int max;
    int a;
    for(int i = N; N > 0; i--){
        a = (int)sqrt((double)i);
        if(a*a == i){
            max = i;
            break;
        }

    }

    printf("%d", max);
}