帮我改改吧！为什么求和和平均数的，排序的不执行啊？？

#include<stdio.h>
#define N 3
struct Student
{
  char id[13];
  int score[3];
  int sum;
  float aver;
};

void input(struct Student stu0[],int count);
void sum_and_aver(struct Student stu1[],int count);
void sort(struct Student stu2[],int count);
void output(struct Student stu3[],int count);

int  main(void)
{
  struct Student stu[N];
  input(stu,N);
  sum_and_aver(stu,N);
  sort(stu,N);
  output(stu,N);
}

void input(struct Student stu0[],int count)
{
  int i;
  printf("请输入 %d 个同学的学号以及数学、英语、计算机成绩:\n",N);
  printf("学号 数学 英语 计算机\n");
  for(i=0;i<N;i++)
  {
    printf("请输入第 %d个同学各项信息:\n",i+1);
    scanf("%s%d%d%d",stu0[i].id,&stu0[i].score[0],&stu0[i].score[1]
      ,&stu0[i].score[2]);
  }
}

void sum_and_aver(struct Student stu1[],int count)
{
  int i,j;
  for(i=0;i<count;i++)
  {
  stu1[i].sum=0;
  for(j=0;j<3;j++)
  stu1[i].sum+=stu1[i].score[j];
  stu1[i].aver=(float)stu1[i].sum/3;
  }
}

void sort(struct Student stu2[],int count)
{
  int i,j;
  struct Student temp;
  for(i=1;i<=count-1;i++)
  for(j=1;j<=count-i;j++)
  if(stu2[j-1].sum<stu2[j].sum)
  {
    temp=stu2[j-1];
    stu2[j-1]=stu2[j];
    stu2[j]=temp;
  }
}

void output(struct Student stu3[],int count)
{
   int i;
   printf("%-14s%-7s%-7s%-7s%-8s%-7s\n","学号",
       "数学","英语","计算机","总分","平均分");
   for(i=0;i<count;i++)
    printf("-14s%-7s%-7s%-7s%-5s%-6.1f\n",stu3[i].id,
    stu3[i].score[0],stu3[i].score[1],stu3[i].score[2],
    stu3[i].sum,stu3[i].aver);
}


//devc++ 4.9.9.2  运行通过
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