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,i,max=1;

    scanf("%lld",&n);
    if(n==2){
        printf("1");
        exit(0);
    }

    for(i=1; i<n;i++){
        if(pow(i,2)>max)
            max= pow(i,2);

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

}