int reverse_replace(char *s,char c)
{
int i,j,r;
char tmp;

r=0;
for(i=0,j=strlen(s)-1;i<j;i++,j--){
tmp=s[i];
s[i]=(s[j]==c)? r++,'\\':s[j];
s[j]=(tmp==c)? r++,'\\':tmp;
}

return r;
}