为啥RE呀.

#include<bits/stdc++.h>
#define N 100005
#define ll long long
using namespace std;
ll n;
stack<ll> c;
ll read(){
    char x;
    ll k=0;
    while((x=getchar())!='.'){
        if(x>'9'||x<'0')return x;
        k=k*10+x-'0';
    }
    return k;
}
int main() {
    ll x,y;
    while((n=read())!='@'){
        switch(n){
            case '+':x=c.top();c.pop();y=c.top();c.pop();c.push(y+x);break;
            case '-':x=c.top();c.pop();y=c.top();c.pop();c.push(y-x);break;
            case '*':x=c.top();c.pop();y=c.top();c.pop();c.push(y*x);break;
            case '/':x=c.top();c.pop();y=c.top();c.pop();c.push(y/x);break;
            default:{
            c.push(n);break;
            }
        }
    }
    cout<<c.top();
    return 0;
}

第五个点re