Miller-Robin's method of determining prime numbers

Explanation : According to Fermat's little theorem, the time complexity is very low. However, there is a certain probability that the judgment will be wrong. Generally, when count==5, the judgment probability is 99%.

code

#include<cstdlib>
#include<ctime>
#include<cstdio>
using namespace std;
const int count=10; //Improve the accuracy of judgment
int modular_exp(int a,int m,int n)
{
    if(m==0)
        return 1;
    if(m==1)
        return (a%n);
    long long w=modular_exp(a,m/2,n);
    w=w*w%n;
    if(m&1)
        w=w*a%n;
    return w;
}

bool Miller_Rabin(int n)
{
    if(n==2)
        return true;
    for(int i=0;i<count;i++)
    {
        int a=rand()%(n-2)+2;
        if(modular_exp(a,n,n)!=a)
            return false;
    }
    return true;
}
intmain()
{
    srand(time(NULL));//Random number seed
    int n;
    while(~scanf("%d",&n))
    {
         if(Miller_Rabin(n))
            printf("YES\n");
         else
            printf("NO\n");
    }
    return 0;
}