讀入優化

/*正數*/
inline void read(int &x)
{
    x=0;char c=getchar();
    while(c<'0'||c>'9') c=getchar();
    while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
}
/*負數*/
inline void read(int &x){
    x=0;char c=getchar();bool f=0;
    if(c=='-'){
        char d=getchar();
        while(d>='0'&&d<='9'){x=x*10+d-'0';d=getchar();}
        f=1;
    }
    else while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
    if(f)x=-x;
}