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 9.2.1) (judge verdict: Wrong Answer)

#include <stdio.h>
int main(void){
    long long N, i, j;
    int cnt = 1;
    
    scanf("%lld", &N);
    
    for(i = N; i > 0; i--){
        for(j = 0; j < N; j++){
            if(i == j * j){
                printf("%lld\n", i);
                cnt = 0;
                break;
            }
        }
        if(cnt == 0){
            break;
        }
    }
    
}