judge5-3.c

#include <stdio.h>
//recursion
int func(int n) {
    if(n == 0) {
        return 0;
    }
    if(n % 2 != 0) {
        return n + func(n - 1);
    } else {
        return - n + func(n - 1);
    } 
}
//for-loop 
int func2(int n) {
    int i, sum = 0;
    for(i = 1; i <= n; i++) {
        if(i % 2 != 0) {
            sum = sum + i;
        } else {
            sum = sum - i;
        }
    }
    return sum;
}
int main() {
    int n;
    scanf("%d", &n);
    printf("Recursive function = %d\n", func(n));
    printf("for loop = %d", func2(n));
    return 0;
}