练习5.6.3节

#include<iostream>
#include<stdexcept>
using namespace std;

int main()
{
    int a,b;
    label: cin>>a>>b;
    try
    {
    if(b==0)throw runtime_error("重输");
    cout<<a/b<<endl;
    }
    catch(runtime_error err)
    {
    cout<<err.what()
        <<"重输"<<endl;

    goto label;
    }
    return 0;
}