#include <stdio.h>

int rec(int n) {
    if (n <= 1) {
        return 1;
    }
    if (n == 2) {
        return 2;
    }
    
    return rec(n - 2) + n;
}

int main(void) {
    int n = 12; 
    
    int wa_k = (n % 2 == 0) ? (n - 1) : n;
    
    int wa_g = (n % 2 != 0) ? (n - 1) : n;
    
    printf("%d以下の正の奇数の和は%d\n", n, rec(wa_k));
    printf("%d以下の正の偶数の和は%d\n", n, rec(wa_g));
    
    return 0;
}