Main.cc:21:1: error: '::main' must return 'int'
   21 | void main() {
      | ^~~~
Main.cc:21:6: error: redefinition of 'int main()'
   21 | void main() {
      |      ^~~~
Main.cc:3:5: note: 'int main()' previously defined here
    3 | int main() {
      |     ^~~~
Main.cc: In function 'int getNNumber(int, int)':
Main.cc:62:23: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   62 |  for (size_t i = 0; i < n; i++) {
      |                     ~~^~~
Main.cc:74:23: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   74 |  for (size_t i = 0; i < n; i++) {
      |                     ~~^~~
Main.cc:75:37: error: 'pow' was not declared in this scope
   75 |   Ndata = Ndata + (tempNNumber[i] * pow(10, i));
      |                                     ^~~
Main.cc: In function 'int main()':
Main.cc:5:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    5 |  scanf("%d ", &in);
      |  ~~~~~^~~~~~~~~~~~