#include 
       
        #include 
        
         #include 
         
          #include 
          
           #include 
           
            using namespace std;//sscanf() – 从一个字符串中读进与指定格式相符的数据//sprintf() – 字符串格式化命令，主要功能是把格式化的数据写入某个字符串中。int main() {    int n, cnt = 0;    double sum = 0, t;    char a[50], b[50];    cin >> n;    for (int i = 0; i < n; i++) {        cin >> a;        sscanf(a, "%lf", &t);//从字符串中读出        sprintf(b, "%.2lf", t);//写入字符串        int flag = 0;        for (int j = 0; j < strlen(a); j++) {            if(a[j] != b[j]) flag = 1;        }        if(flag || t < -1000 || t > 1000) {            printf("ERROR: %s is not a legal number\n", a); continue;        }else{            sum += t;            cnt++;        }    }        if(cnt == 0) cout << "The average of 0 numbers is Undefined\n";    else if(cnt == 1) printf("The average of 1 number is %.2lf\n", sum);    else printf("The average of %d numbers is %.2lf\n", cnt, sum / cnt);        return 0;}