Hey so here is my solution for problem 1A. Theatre Square:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main()
{
    int n, m, a;
    scanf("%i %i %i", &n, &m, &a);
    long long int x;
    x = (long long int)ceil((float)m/a)*ceil((float)n/a);
    printf("%lli", x);
 
    return 0;
}

But codeforce's verdict is Wrong answer on test 16:

Test: #16, time: 15 ms., memory: 4 KB, exit code: 0, checker exit code: 1, verdict: WRONG_ANSWER Input 1000000000 1000000000 999999999 Output 1 Answer 4 Checker Log wrong answer 1st numbers differ — expected: '4', found: '1'

However, if I check the input manually, I'm receiving the output 4 which is exactly what I'm supposed to get. Is it a bug of some sort? And if it is, what can I do now?