int read()
{
int p,data=0;
char ch=0;
while ((ch!='-') && ch<'0' || ch>'9') ch=getchar();
if (ch=='-')
{
p=-1;
ch=getchar();
} else p=1;
while (ch>='0' && ch<='9') data=data*10+ch-'0',ch=getchar();
return data*p;
}