快速读入
提高读入数据的效率，返回值为第一个读入的整数。
inline int read()
{
int x = 0, f = 1; char ch = getchar();
while (ch < '0' || ch>'9'){if (ch == '-') f = -1; ch = getchar();}
while (ch >= '0' && ch <= '9') {x = x * 10 + ch - 48; ch = getchar();}
return x * f;
}提高读入数据的效率，返回值为第一个读入的整数。
inline int read()
{
int x = 0, f = 1; char ch = getchar();
while (ch < '0' || ch>'9'){if (ch == '-') f = -1; ch = getchar();}
while (ch >= '0' && ch <= '9') {x = x * 10 + ch - 48; ch = getchar();}
return x * f;
}