divisors.cpp

#include<bits/stdc++.h>
using namespace std;

#define M 1000000

bool mark[M];

vector<int>prime;

void sieve()
{
    int i,j;
        prime.push_back(2);
        for(i=3;i*i<M;i+=2)
        {
            if(mark[i]==false)
            {
                for(j=i*i;j<M;j+=2*i)
                    mark[j]=true;
            }
        }
        for(i=3;i<M;i+=2)
        {
            if(mark[i]==false)
                prime.push_back(i);
        }

}


int divisors(int n)
{
    int divisor=1;
    int k=n;
    for(int i=0;prime[i]<k;i++)
    {
        if(n%prime[i]==0)
        {
            int count=1;
            while(n%prime[i]==0)
            {
                n/=prime[i];
                count++;
            }
            divisor*=count;
        }
    }

    return divisor;
}

int main()
{
    int n,i,k;
    sieve();
    scanf("%d",&n);
    k=divisors(n);

    printf("%d\n",k);

    return 0;
}