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>

#define MAX(a,b) (a > b ? a : b)
#define MIN(a,b) (a < b ? a : b)
const int inf = 1000000000; // 10^9

int main(){
   int n;scanf("%d",&n);
   for(int i = n;i > 0;i--){
      for(long int j = 0;j < n/2;j++){
         if(i==j*j){
            printf("%ld\n",j);
            printf("%d",i);
            return 0;
         }
      }
   }
}