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<math.h>
#include<stdlib.h>
int main(){

     long long int n;

    scanf("%lld",&n);
if(n>=1 && n<=pow(10,9)){
    for(int i=1; i<n;i++){
            
        if(n==2){
            printf("1");
            exit(0);
        }
        if(i==sqrt(n)){
            printf("%d",(int)pow(i,2));
            exit(0);
        }

        else if(i>sqrt(n)){
            printf("%d",(int)pow(i-1,2));
            exit(0);
        }
    }
}

}