快读

char buf[1<<23],*p1=buf,*p2=buf;
#define getchar() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<23,stdin),p1==p2)?EOF:*p1++)
inline int read() {
    int x = 0, f = 1;
    char ch = getchar();
    for (; !isdigit(ch); ch = getchar()) if (ch == '-') f = -f;
    for (; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + (ch ^ 48);
    return x * f;
}