Main.cc: In function ‘void print(int)’: Main.cc:20:2: error: ‘fputchar’ was not declared in this scope fputchar((x%10)|0x30); ^~~~~~~~ Main.cc:20:2: note: suggested alternative: ‘putchar’ fputchar((x%10)|0x30); ^~~~~~~~ putchar Main.cc: In function ‘int main()’: Main.cc:53:9: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("seq.in","r",stdin); ~~~~~~~^~~~~~~~~~~~~~~~~~~~ Main.cc:54:12: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("seq.out","w",stdout); ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~