Compilare: user.cpp: In function ‘int f3()’: user.cpp:37: warning: unused variable ‘sol’ user.cpp: In function ‘int f4()’: user.cpp:54: warning: array subscript has type ‘char’ user.cpp: In function ‘int main()’: user.cpp:64: warning: comparison between signed and unsigned integer expressions user.cpp:100: warning: array subscript has type ‘char’ user.cpp:100: warning: array subscript has type ‘char’ user.cpp:61: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:62: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:97: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:99: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result