void xoakhoangtrang(char *s)
{
char *c=strstr(s," ");
while(c!=NULL)
{
int t=strlen(s)-strlen(c);
for(int i=t;i<strlen(s);i++)
s[i]=s[i+1];
c=strstr(s," ");
}
if(s[0]==' ')
s=s+1; //xoa khang trang dau chuoi
int n=strlen(s);
if(s[n-1]==' ')
s[n-1]='\0';//xoa khoang trang cuoi chuoi
cout<<s; //for(int i=0;i<n;i++)
//cout<<s[i];
}