B. Sherlock and his girlfriend

#include<cstdio> #include<cstring>#include<iostream>#include<string>using namespace std;int arr[100100];int main(){    for(int i=2;i<100100;i++)    if(!arr[i])    for(int j=2;i*j<100100;j++)    arr[j*i]=1;    int num;    cin>>num;    int key=0;    if(num>=3)    {        cout<<2<<endl;        for(int i=1;i<=num;i++)    {       if(key)printf(" ");    if(arr[i+1])printf("1");    else if(!arr[i+1])printf("2");    key=1;    }    }    else if(num==2)    {        cout<<1<<endl;        cout<<"1 1";    }    else if(num==1)    {cout<<1<<endl<<1;    }    return 0;}