#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;
}

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