#include"stdio.h"
main()
{
    float x,y;
    printf("請輸入x的值:");
    scanf("%f",&x);
    if(x<1)
    y=x;
    else if(1<=x<10)
    y=2*x-4;
    else
     y=3*x-10;
    printf("%f\n",y);
}