Basic Calculator

#include <iostream>
#include <string>
using namespace std;
int main() {
    string i;
    string newString ="Commands: \n ;calculator \n What would you like me to do, sir?: ";
    cout<<newString;
    cin>>i;
    if (i == ";calculator"){
        int a,b;
        newString = "\n Multiplication \n Division \n Addition \n Subtraction";
        cout<<newString;
        newString = "\n Choose one: ";
        cout<<newString;
        cin>>i;
        if (i == "Multiplication") {
            newString = "Insert first number here: ";
            cout<<newString;
            cin>>i;
            a = stoi(i);
            newString = "Insert second number here: ";
            cout<<newString;
            cin>>i;
            b=stoi(i);
            cout<<a*b;
        }
        else{
            if (i == "Division") {
            newString = "Insert dividend here: ";
            cout<<newString;
            cin>>i;
            a = stoi(i);
            newString = "Insert divisor here: ";
            cout<<newString;
            cin>>i;
            b=stoi(i);
            cout<<a/b;
            }
            else{
                if (i == "Subtraction") {
                newString = "Insert first number here: ";
                cout<<newString;
                cin>>i;
                a = stoi(i);
                newString = "Insert second number here: ";
                cout<<newString;
                cin>>i;
                b=stoi(i);
                cout<<a-b;
                }
                else{
                    if (i == "Addition") {
                        newString = "Insert first number here: ";
                        cout<<newString;
                        cin>>i;
                        a = stoi(i);
                        newString = "Insert second number here: ";
                        cout<<newString;
                        cin>>i;
                        b=stoi(i);
                        cout<<a+b;
                    }
                }
            }
        }
    }
    else{
        cout<<"Not a command!";
        return 0;
    }
}