代码编写不会，一道数学题

int main()
{                   
    int x=0,y;
    scanf("%d",&x);
    if(x<0)
        y=-x;
    else if(x<5)
        y=2*x+1;
    else
        y=5*x-1;
    printf("y=%d\n",y);
    
    return 0;    
}