Hello. I am trying to run a simple postfix notation code. It builds but doesn't run. Can anyone tell me if it's my code that is stopping it from running?

Here is my code:

```
`int main(int argc, char *argv[]){`
char *a = argv[1];
int i, div, N = strlen(a);
stack<int> save(N);
cout << "Enter the postfix expression";
cin >> a;
for(i = 0; i<N; i++){
if(a[i] == '+')
save.push(save.pop() + save.pop());
if(a[i] == '*')
save.push(save.pop() * save.pop());
if(a[i] == '-')
save.push(save.pop() - save.pop());
if(a[i] == '/')
save.push(save.pop() / save.pop());
if((a[i] >= '0') && (a[i] <= '9'))
save.push(a[i] -'0');
//while ((a[i] >= '0') && (a[i] <= '9'))
// save.push(10*save.pop() + (a[i++]-'0'));
}
cout << save.pop() <<endl;
return 0;
}`
```