Add 1 by 1 numbers when user input in for loop c++

// Student attendence

#include <iostream>
#include <string>
#include <conio.h>
#include <limits>

using namespace std;

int main ()
{

      cout<<"Enter Attendance for CP : ";

      int cptotal;

	   for(int i=0;i<31;i++){
		
           cin>>cptotal;	
		
           if(cptotal==1)
	     cptotal=cptotal+1;

	   }
		
	   cout<<cptotal;

	}

  return 0;

}