for the problem http://codeforces.com/contest/914/problem/A

Your code here...

#include "bits/stdc++.h"
     using namespace std;
     const int N = 1e3 + 3;
     const int M = 1e6 + 6;
     int n;
     int arr[N];
     int mark[M];
     int val;
     int main(){
             scanf("%d" , &n);
             val = -M;
             for(int i = 0 ; i * i < M ; ++i)
                {
         mark[i * i] = 1;
            }
            for(int i = 1 ; i <= n ; ++i)
                {
        scanf("%d" , arr + i);  
        if(arr[i] >= 0 && mark[arr[i]]){
       continue;
        }
        val = max(val , arr[i]);
           }
          printf("%d\n" , val);
    }

Also please explain the method of Input for long range of values.. I generally use long long int for such input range. is it good practice??