user: 请从给定的汇编指令推导出C源代码:

```asm
<main>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x20,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  lea    D45(%rip),%rax
  mov    %rax,%rdi
  call   <printf@plt>
  lea    -0x10(%rbp),%rsi
  lea    -0x14(%rbp),%rcx
  lea    -0x18(%rbp),%rdx
  lea    -0x1c(%rbp),%rax
  mov    %rsi,%r8
  mov    %rax,%rsi
  lea    D79(%rip),%rax
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <scanf@plt>
  lea    D21(%rip),%rax
  mov    %rax,%rdi
  call   <printf@plt>
  lea    -0xc(%rbp),%rax
  mov    %rax,%rsi
  lea    D57(%rip),%rax
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <scanf@plt>
  movss  -0xc(%rbp),%xmm0
  movss  -0x10(%rbp),%xmm1
  comiss %xmm1,%xmm0
  jb     L48
  movss  -0xc(%rbp),%xmm0
  movss  -0x14(%rbp),%xmm1
  comiss %xmm1,%xmm0
  jb     L1
  movss  -0xc(%rbp),%xmm0
  movss  -0x18(%rbp),%xmm1
  comiss %xmm1,%xmm0
  jb     L77
  movss  -0xc(%rbp),%xmm0
  movss  -0x1c(%rbp),%xmm1
  comiss %xmm1,%xmm0
  jb     L33
  lea    D30(%rip),%rax
  mov    %rax,%rdi
  call   <printf@plt>
  jmp    L7
L33:
  lea    D81(%rip),%rax
  mov    %rax,%rdi
  call   <printf@plt>
  jmp    L7
L77:
  lea    D2(%rip),%rax
  mov    %rax,%rdi
  call   <printf@plt>
  jmp    L7
L1:
  lea    D89(%rip),%rax
  mov    %rax,%rdi
  call   <printf@plt>
  jmp    L7
L48:
  lea    D12(%rip),%rax
  mov    %rax,%rdi
  call   <printf@plt>
L7:
  mov    $0x0,%eax
  mov    -0x8(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L8
  call   <__stack_chk_fail@plt>
L8:
  leave
  ret
```

tool_calls: name: disassemble_data
arguments: data_label: D45
datatype: string
name: disassemble_data
arguments: data_label: D79
datatype: string
name: disassemble_data
arguments: data_label: D21
datatype: string
name: disassemble_data
arguments: data_label: D57
datatype: string
name: disassemble_data
arguments: data_label: D30
datatype: string
name: disassemble_data
arguments: data_label: D81
datatype: string
name: disassemble_data
arguments: data_label: D2
datatype: string
name: disassemble_data
arguments: data_label: D89
datatype: string
name: disassemble_data
arguments: data_label: D12
datatype: string

tool: D45: Enter thresholds for A, B, C, D
in that order, decreasing percentages > 

tool: D79: %f%f%f%f

tool: D21: Thank you. Now enter student score (percent) >

tool: D57: %f

tool: D30: Student has an A grade


tool: D81: Student has an B grade


tool: D2: Student has an C grade


tool: D89: Student has an D grade


tool: D12: Student has failed the course


assistant: ```c
int main() {
  float A, B, C, D, Grade;
  printf("Enter thresholds for A, B, C, D\nin that order, decreasing percentages > ");
  scanf("%f"
        "%f"
        "%f"
        "%f",
        &A, &B, &C, &D);
  printf("Thank you. Now enter student score (percent) >");
  scanf("%f", &Grade);
  if (Grade >= D) {
    if (Grade >= C) {
      if (Grade >= B) {
        if (Grade >= A) {
          printf("Student has an A grade\n");
        } else {
          printf("Student has an B grade\n");
        }
      } else {
        printf("Student has an C grade\n");
      }
    } else {
      printf("Student has an D grade\n");
    }
  } else {
    printf("Student has failed the course\n");
  }
  return 0;
}
```