请问为什么我这个first.id输出的是烫tangtang,但last.id输出是正常的

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CS301111 15:30:28 17:00:10
SC3021234 21:45:00 11:25:25
CS301133 08:00:00 21:58:40
这是测试用例,first和last,我基本上是用一种方法写出来的，为什么first.id 就是烫？/

#include<stdio.h>
#include<stdlib.h>
typedef struct time {
    int hour;
    int min;
    int sec;
} time;
typedef struct person {
    char id[15];
    time intime;
    time outtime;
} person;
int compare(time a,time b) {
    if (a.hour > b.hour)
        return 1;
    else if (a.hour < b.hour)
        return 0;
    else {
        if (a.min > b.min)
            return 1;
        else if (a.min < b.min)
            return 0;
        else {
            if (a.sec >= b.sec)
                return 1;
            else if (a.sec < b.sec)
                return 0;
        }
    }
}
int main() {
    person needcheck, first, last;
    *first.id = "no"; *last.id = "no";
    int a;
    scanf("%d", &a);
    for (int i = 0; i < a; i++) {
        scanf("%s %d:%d:%d %d:%d:%d", needcheck.id, &needcheck.intime.hour, &needcheck.intime.min, &needcheck.intime.sec, &needcheck.outtime.hour, &needcheck.outtime.min, &needcheck.outtime.sec);
        if (last.id == "no") {
            last = needcheck;
        }
        else {
            if (!compare(needcheck.outtime, last.outtime) == 1)
                last = needcheck;
        }
        if (first.id == "no") {
            first = needcheck;
        }
        else {
            if (compare(needcheck.intime, first.intime) == 1)
                first = needcheck;
        }
    }
    printf("%s %s",last.id,first.id);
    return 0;
}