Problem:
Score : 100 points

Problem Statement

In K-city, there are n streets running east-west, and m streets running north-south. Each street running east-west and each street running north-south cross each other. We will call the smallest area that is surrounded by four streets a block. How many blocks there are in K-city?

Constraints

2 ≤ n, m ≤ 100

Input

Input is given from Standard Input in the following format:

n m

Output

Print the number of blocks in K-city.

Sample Input 1

3 4

Sample Output 1

6

There are six blocks, as shown below:

Sample Input 2

2 2

Sample Output 2

1

There are one block, as shown below:

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>

int main()
{
  int n, i;
  int ai;
  int four = 0;
  int even = 0;
  int odd = 0;

  scanf("%d", &n);

  for(i = 0; i < n; i++){
    scanf("%d", &ai);
    if(ai%4 == 0){
      four++;
    }else if(ai % 4 == 2){
      even++;
    }else{
      odd++;
    }
  }
  if(four >= odd + 1){
    printf("Yes");
  }else{
    printf("No");
  }

  return 0;
}