求大佬帮忙！只能过一个点

#include <iostream>
using namespace std;
const int MAXN=1000;
string S;
int A[MAXN];
int Stack[MAXN],top;

int main(int argc, const char * argv[]) {
    // insert code here...
    cin>>S;
    int l=S.size();
    int x,y,z;
    for(int i=0;i<l;i++)
    {
        if((S[i]>='0')&&(S[i]<='9'))
        {
            Stack[top]=S[i]-'0';
            top++;
        }
        if(S[i]=='+')
        {
            y=Stack[top-1];
            x=Stack[top-2];
            top=top-2;
            z=x+y;
            Stack[top]=z;
            top++;
        }
        if(S[i]=='-')
        {
            y=Stack[top-1];
            x=Stack[top-2];
            top=top-2;
            z=x-y;
            Stack[top]=z;
            top++;
        }
        if(S[i]=='*')
        {
            y=Stack[top-1];
            x=Stack[top-2];
            top=top-2;
            z=x*y;
            Stack[top]=z;
            top++;
        }
        if(S[i]=='/')
        {
            y=Stack[top-1];
            x=Stack[top-2];
            top=top-2;
            z=x/y;
            Stack[top]=z;
            top++;
        }
    }
    int ans=Stack[top-1];
    cout<<ans;
    return 0;
}