#include <stdio.h>

unsigned char student1 = 0x6B;
unsigned char student2 = 0xC6;

unsigned char changeClass(unsigned char student, unsigned char cls) {
    student &= 0x3F;
    student |= cls << 6;
    return student;
}

void printStudent(unsigned char student) {
    printf("クラス: %d 出席番号: %d 性別: %d\n", student >> 6, student >> 1 & 0x1F , student & 0x01);
}

int main(void) {
    student1 = changeClass(student1, 2);
    printStudent(student1);
    printStudent(student2);
}