求助！第一遍前面两个测试点通不过，改过以后刚好后面三个测试点过不了是什么道理啊

#include <stdio.h>

int main()
{
    unsigned int n;
    scanf("%d" ,&n);
    printf("Today, I ate %u apple%c.",n ,n>1?'s':'\0');
    return 0;
}

#include <stdio.h>

int main()
{
    unsigned int n;
    scanf("%d" ,&n);
    printf("Today, I ate %u apple.%s",n ,n>1?"\bs.":"\0");
    return 0;
}