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 main (void){
    int a,b[100000],c,i;
    printf("please input the integer:");
    scanf("%d",&a);

    for(i=0;i<100000;i++){
        b[i]=(i+1)*(i+1);
        if(b[i] <= a){
            c = b[i];
        }
        else{
            break;
        }
    }
    printf("%d",c);
    return 0;
}