While循环和if/else语句工作不正常

我遇到的问题是，当我运行代码时，它会正确添加，但当运行if或else语句时，什么都不会发生。它总是刚刚结束。

#include <iostream>
using namespace std;
int main()
{
int firstNumber;
int secondNumber;
int sum;
char restart = 1;
while (restart == 1)
{
cout<<"Welcome to My Calculator!nn";
cout<<"What is the first number you would like to add?nn";
cin>>firstNumber;
cout<<"What is the second number you would like to add?nn";
cin>>secondNumber;
cout<<"Wonderful! Getting together your result now....nn";
sum = firstNumber +   secondNumber;
cout<< sum<<endl;
cout<<"If you have another question, just enter 1, if not press 2!nn";
cin>>restart;
if (restart == 1)
{
cout<<"No problem!nn";
}
else
{
cout<<"Goodbye!";
}

}
return 0;
}