编了一个上午，在机器上运行答案对了，可是交上来就是runtime error,气死我了。各位帮帮忙阿。。。

#include <stdio.h>
#include <string.h>

void main()
{
	int n,i,j,k,l;
	int bal[2],unbal;
	int m=0,len;
	char left[3][5],right[3][5],result[3][5];
	char s[20];
	scanf("%d",&n);
	
	for(i=0;i<n;i++)
	{
		for(j=0;j<3;j++)
			scanf("%s %s %s",left[j],right[j],result[j]);	
				
					
		for(j=0;j<3;j++)
		{
			if(result[j][0]=='e')	{bal[m]=j;m++;}
			else unbal=j;
			if(j==2) break;
		}
		
		strcpy(s,left[bal[0]]);
		strcat(s,right[bal[0]]);
		len=strlen(s);
		
		for(k=0;k<5;k++)
		{
			if(left[bal[0]][k]!=left[bal[1]][k])
			{s[len]=left[bal[1]][k];
			len++;}
		}
		for(k=0;k<5;k++)
		{
			if(right[bal[0]][k]!=right[bal[1]][k])
			{s[len]=right[bal[1]][k];
			len++;}
		}
		len=strlen(s);	
		
		for(k=0;k<4;k++)
		{	for(l=0;l<len;l++)
			{	if(left[unbal][k]==s[l]) break;
				else if(l==len-1&&result[unbal][0]=='u') 
				{	printf("%c is the counterfeit coin and it is heavy.\n",left[unbal][k]);
					break;
				}	
				else if(l==len-1&&result[unbal][0]=='d')	
				{	printf("%c is the counterfeit coin and it is light.\n",left[unbal][k]);
					break;
				}
			}
		}
		for(k=0;k<4;k++)
		{	for(l=0;l<len;l++)	
			{	if(right[unbal][k]==s[l]) break;
				else if(l==len-1&&result[unbal][0]=='u') 
				{	printf("%c is the counterfeit coin and it is light.\n",right[unbal][k]);
					break;
				}
				else if(l==len-1&&result[unbal][0]=='d')	
				{	printf("%c is the counterfeit coin and it is heavy.\n",right[unbal][k]);
					break;
				}
			}
		}
	}
}