so i am having a trouble in subtracting a number that contains 3 in c++ i just couldnt get it right maybe you can help me in analyzing

code:
Code:
#include<iostream>
#include<conio.h>
using namespace std;
int main()
{
	int integer, sum=0;
	cout<<"Enter an integer: ";
	cin>>integer;
	for (int i = 1; i <= integer; ++i) 
	{	 
		sum += i;
		
		if(i==33 || i%10 == 3)
		{
			i = sum - i;
		}
		
    }


    cout << "  The Sum is = " << sum;


    getch();
    return 0;
}