reduce string

wats the problem with this code for reduce string problem given in hard practice section please tell?

#include<stdio.h>
#include<string.h>
int main()
{
int count[256]={0},i,j=0,n,k=0;
char s[250],sb[20];
scanf("%s",&s);
for(i=0;s[i]!=’\0’;i++)
{
count[s[i]]++;

}


scanf("%d",&n);

while(n--)
{
	 scanf("%s",&sb);
for(i=0;sb[i]!='\0';i++)
	{
		for(j=0;s[j]!='\0';j++)
		{
			if(s[j]==sb[i])
			{
			count[s[j]]--;
			s[j]=-2;
			break;
			}
		}

	  }


}

for(i=0;i<255;i++)
{
       if(count[i]!=0 && count[i]>0)
	{
	  k+=count[i];

	}

}
printf("%d",k);

return 0;
}

//