where is the wrong?

#include<iostream>
using namespace std;
int main(){
    string n;cin>>n;
    int a1=(n[0]-'0')*10+n[1]-'0';
    int a2,ans;
    if (n[2]==' ' && n[4]==' '){
        a2=(n[5]-'0')*10+n[6]-'0';
        switch(n[3]){
            case '+':
                cout<<a1+a2;
                break;
            case '-':
                cout<<a1-a2;
                break;
            case '*':
                cout<<a1*a2;
                break;
            case '/':
                cout<<a1/a2;
                break;
            case '%':
                cout<<a1%a2;
                break;
        }
    }else{
        a2=(n[3]-'0')*10+n[4]-'0';
        switch(n[2]){
            case '+':
                cout<<a1+a2;
                break;
            case '-':
                cout<<a1-a2;
                break;
            case '*':
                cout<<a1*a2;
                break;
            case '/':
                cout<<a1/a2;
                break;
            case '%':
                cout<<a1%a2;
                break;
        }
    }
    return 0;
}