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: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
    long long  R;
    scanf("%lld",&R);
    long long  temp;
    long long j;
    for(int i=2;i<R/2;i++)
    {
        temp=i*i;
        if(temp==R)
        {
            j=i;
            break;
        }
        if(temp>R)
        {
            j=i-1;break;
        }
    }
    printf("%lld\n",j*j);
    return 0;
}