编译无误，运行出错

#include <iostream>
#include<stdlib.h>
#include <iomanip>
using namespace std;


int main()
{
    int id[5];
    int china[5]={75,80,85,52,86};
    int math[5];
    int i,max=0,y,x;
    int j[8];
    int sum[5],sum1[5];
    for(i=0;i<5;i++)
    {
        cout<<"请输入学号"<<endl;
        cin>>id[i];
        cout<<"请输入数学成绩"<<endl;
        cin>>math[i];
    }
    for(i=0;i<5;i++)
    {
        sum[i]=china[i]+math[i];
        sum1[i]=sum[i]; //为了不改变sum数组的值，先将sum赋值给 sum1
    }
    for(i=0;i<5;i++) //将总成绩最大的数数组下标赋值到J数组，从而得到名次
    {
      
        for(y=0;y<5;y++)
        {
            if(max<sum1[y])
            {
                max=sum1[y];
                j[i]=y;
            }
        }
        x=j[i];
        sum1[x]=0;
    }
    cout<<"学号  语文  数学  总分  均分  名次"<<endl;
    for(i=0;i<5;i++)
    {
        y=j[i];
        cout<<id[y]<<setw(6)<<china[y]<<setw(6)<<math[y]<<setw(6)<<sum[y]<<setw(6)<<sum[y]/2<<setw(6)<<i+1<<endl;
    }
    return 0;
}