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>

int main(void) {
	int n,i,a=0;
	scanf("%d",&n);
	if(n==2) {printf("%d",1); return 0;}
	for(i=0;i<n;i++) {
		a=i*i;
		if(a>n) {i--; break;}
	}
	printf("%d\n",i*i);
	return 0;
}