guess the obtained marks out of total and assign a grade to it

#include<stdio.h>
int main()
{
    int bio,chem,phy,marks,obt;
    
    printf("enter bio marks");
    scanf("%d",&bio);
    
    printf("enter chem  marks");
    scanf("%d",&chem);
    
    printf("enter phy marks");
    scanf("%d",&phy);
    
    obt=phy+chem+bio;
    
    printf("your total out of 255 is %d",obt);
    
    if (obt<=255 && obt>200)
                  {
                      printf("your grade is A");
                  }
    else if (obt<=200 && obt >150)
                  {
                      printf("ypur grade is B");
                  }
    else if (obt<=150 && obt> 100)
                  {
                      printf("your grade is C");
                  }
    else if (obt < 100)
                  {
                      printf("u are fail ");
                  }
    else
                  {
                      printf("invalid number");
                  }
                
}