#include<iostream.h>
main()
{
    int x,sum=0;
    //定義標(biāo)號(hào)L1
L1: cout<<"x=";
    cin>>x;
    if (x==-1)
       goto L2;          //無(wú)條件轉(zhuǎn)移語(yǔ)句，轉(zhuǎn)到L2語(yǔ)句處
    else
       sum+=x;
    goto L1;             //無(wú)條件轉(zhuǎn)移語(yǔ)句，轉(zhuǎn)到L1語(yǔ)句處
    //定義標(biāo)號(hào)L2
L2: cout<<"sum="<<sum<<endl;
}