Compilare: user.cpp: In function ‘int gen(int)’: user.cpp:12: warning: comparison between signed and unsigned integer expressions user.cpp:20: warning: comparison between signed and unsigned integer expressions user.cpp:31: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:45: warning: format ‘%s’ expects type ‘char*’, but argument 2 has type ‘char (*)[21]’ user.cpp:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:44: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:45: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘int gen(int)’: user.cpp:39: warning: control reaches end of non-void function