Compilare: user.cpp: In function ‘int main()’: user.cpp:14: warning: format ‘%s’ expects type ‘char*’, but argument 2 has type ‘char (*)[2000005]’ user.cpp:11: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:12: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:14: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void make_prefix()’: user.cpp:58: warning: suggest parentheses around assignment used as truth value