int read() { int s = 0, f = 1; char ch = getchar(); while(!isdigit(ch)) { if(ch == '-') f = -1; ch = getchar(); } while(isdigit(ch)) { s = s * 10 + ch - '0'; ch = getchar(); } return s * f; }
void write(int x) { if(x < 0) { putchar('-'); x = -x; } if(x > 9) write(x/10); putchar(x % 10 - '0'); return; }