Main.cc:8:11: error: ‘::main’ must return ‘int’ void main() ^ Main.cc: In function ‘int main()’: Main.cc:13:7: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ~~~~~^~~~~~~~~~ Main.cc:25:8: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result [-Wunused-result] system("pause"); ~~~~~~^~~~~~~~~