hurr durr

so I just started programing like two days ago (c++) , and Im doing basic exercises, nothing really complicated, but for some reason I cant get this, any help is welcome

Pd: I have never been so scared of posting in a board
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#include <iostream>

using namespace std;

int main()
{
  int n;
  int c;
  int crash;
  cout<<"Insert a number"<<endl;
  cin>>n;

  /*do{
    if(n%c==0){
     crash = 1;
    }
    c = c - 1;
    }while(c == 1);*/

    for(c = n-1; c == 1; c--){
      if(n%c == 0){
      crash = 1;
     }
    }


    if(crash == 1){
    cout<<"The number is prime"<<endl;
    } else{
    cout<<"The number is not prime"<<endl;}

    return 0;
  }

and that means...