Eroare de compilare: user.cpp: In function ‘void read()’: user.cpp:28: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void solve()’: user.cpp:53: warning: suggest explicit braces to avoid ambiguous ‘else’ user.cpp: In function ‘void write()’: user.cpp:67: error: ‘exit’ was not declared in this scope