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>

int AbsV(int num){
  if(num >= 0) return num;
  if(num < 0) return num * -1;
}

int main(){
  int N, min, ans = 0;
  scanf("%d", &N);
  min = N;
  while(1){
    if(min < AbsV(N - (ans * ans))){
      ans--;
      break;
    }
    ans++;
  }
  printf("%d", ans * ans);
  return 0;
}