P5728，例子过了，但是0分，多次调试也没有发现错误，求指导

#include<stdio.h>
int main()
{
	int N,a[1010][3],b[1010],number=0;\\**b来记录总成绩分差**
	scanf(" %d", &N);
	for (int i = 0; i < N; i++)
	{
		b[i] = 0;
		for (int j = 0; j < 3; j++)
		{
			scanf(" %d", &a[i][j]);
			b[i] += a[i][j];
		}
	}//**此段存入成绩信息，调试无误**
	for (int i = 0; i < N; i++)
	{
		for (int j = 0; j < i; j++)
		{
			int num = 0;
			for (int k = 0; k < 3; k++)
			{
				int m = a[i][k] - a[j][k];
				if (m <= 5 && m >= -5 ) num++;\\**num是单科分差在5以内的科目个数**
			}
			int o = b[i] - b[j];
			if (num == 3 && o <= 10 && o >= -10) number++;
		}
	}
	printf("\n%d", number);
	return 0;
}