结构体问题

#include <stdio.h>
#include <math.h>
struct teacher
{
    int gznum;                    /* 工资卡号 */
    char name[20];               /* 姓名 */
    int sex;                     /* sex=1(男),0(女) */
    int year,month;             /* 出生年月 */
    union marriage
    {
        char marriage[20];
    }u1,u2;
}teachers;
int main()
{
    printf("Enter gznum:\n");
    scanf("%d",&teachers.gznum);
    printf("Enter name:\n");
    scanf("%s",&teachers.name[20]);
    printf("Enter sex(1/0):\n");
    scanf("%d",&teachers.sex);
    printf("Enter born of year-month:\n");
    scanf("%d-%d",&teachers.year,&teachers.month);

    printf("%d\t%s\t%d\t%d-%d\t%d\n",teachers.gznum,teachers.name[20],teachers.sex,teachers.year,teachers.month,teachers.u1.marriage[20]);
    return 0;
}