#include<stdio.h>


void bai1(){
	int n;

    printf("nhap n : ");
    scanf("%d",&n);
    printf("so nguyen nhap vao la %d\n",n);
    for (int i = 1; i <= n; ++i) {
    	if(n % i == 0){
       		printf("%d\n",i);
        }
    }	
}
void bai2(){
	int n, b, c;
    int d = 1; 

    printf("nhap n : ");
    scanf("%d", &n);

    b = n % 10;
    n /= 10;

    while (n > 0) {
        c = n % 10;
        if (c > b) {
            d = 0; 
            break;
        }
        b = c;
        n /= 10;
    }

    if (d) {
        printf("tang dan tu trai qua phai\n");
    } else {
        printf("khong tang dan tu trai qua phai\n");
    }

}
int bai3(){
    int n,x;

    printf("nhap n : ");
    scanf("%d", &n);

    printf("nhap x : ");
    scanf("%d", &x);

    int a;
    int b = 2; 

    for (int i = 1; i <= n; ++i) {
        if (i % 2 == 0) {
            a -= x / b;
        } else {
            a += x / b;
        }
        b += 2; 
    }

    printf(" S(x, n) là: %d\n", a);
	
}
int main(){
	printf("bai 1 : \n");
	bai3();
	
}