输入外挂

//包含负数

int readf(){int t=0,flag=1;char c=getchar();while(c<'0'||c>'9'||c=='-'){if(c=='-')flag=-1;c=getchar();}while(c>='0'&&c<='9'){t=t*10+c-'0';c=getchar();}return t*flag;}

//只有正整数

int read(){int ret=0;char ch=getchar();while(ch<'0'||ch>'9') ch=getchar();for(;ch>='0'&&ch<='9';ch=getchar()) ret=ret*10+ch-'0';return ret;}

namespace fastIO { 
    #define BUF_SIZE 100000 
    bool IOerror = 0; 
    inline char nc() { 
        static char buf[BUF_SIZE], *p1 = buf + BUF_SIZE, *pend = buf + BUF_SIZE; 
        if(p1 == pend) { 
            p1 = buf; 
            pend = buf + fread(buf, 1, BUF_SIZE, stdin); 
            if(pend == p1) { 
                IOerror = 1; 
                return -1; 
            } 
        } 
        return *p1++; 
    } 
    inline bool blank(char ch) { 
        return ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t'; 
    } 
    inline void read(int &x) { 
        char ch; 
        while(blank(ch = nc())); 
        if(IOerror) 
            return; 
        for(x = ch - '0'; (ch = nc()) >= '0' && ch <= '9'; x = x * 10 + ch - '0'); 
    } 
    #undef BUF_SIZE 
}; 
using namespace fastIO;

namespace fastIO
{
#define BUF_SIZE 100000
    char bf[BUF_SIZE],*p1=bf,*p2=bf;
#define nc() (p1==p2&&(p2=(p1=bf)+fread(bf,1,BUF_SIZE,stdin),p2==p1)?-1:*p1++)
    inline int read(){
        int x=0;char ch=nc();for(;ch<'0'||ch>'9';ch=nc());
        for(;ch<='9'&&ch>='0';x=x*10+ch-48,ch=nc());
        return x;
    }
#undef BUF_SIZE
};

template<class T> void read(T&num)
{
    char CH;
    bool F=false;
    for(CH=getchar(); CH<'0'||CH>'9'; F= CH=='-',CH=getchar());
    for(num=0; CH>='0'&&CH<='9'; num=num*10+CH-'0',CH=getchar());
    F && (num=-num);
}
int stk[70], tp;
template<class T> inline void print(T p)
{
    if(!p)
    {
        puts("0");
        return;
    }
    while(p) stk[++ tp] = p%10, p/=10;
    while(tp) putchar(stk[tp--] + '0');
    putchar('\n');
}