Mã chấm: 257025

Main.cc: In function ‘int main()’:
Main.cc:38:12: error: ‘a’ was not declared in this scope
     while (a--) {
            ^
Main.cc:40:10: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~