Số nguyên tố Test6.c

// Kiem tra toi căn n va neu la so chan thong bao khong phai nguyen to luon
#include <stdio.h>
int nt(int n){
    int i,kt; // i la bien chay, kt la bien kiem tra nguyen to
    kt=1; // coi n la so nguyen to
    if (n==2) kt=1;
    else
        if ((n==1) || (n%2==0)) kt=0;
        else
            for (i=3;i<=sqrt(n);i+=2){
                if (n%i==0){
                    kt=0; // n khong phai la so nguyen to
                    break;
                }
            }
    return kt;
}
int main(){
    int n;
    printf("Nhap n= ");
    scanf("%d",&n);
    if (nt(n)==0) printf("Khong la so nguyen to");
    else printf("La so nguyen to");
    return 0;
}