Compilare: user.cpp: In function ‘void read()’: user.cpp:20: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void solve1()’: user.cpp:85: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void solve2()’: user.cpp:104: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void solve3()’: user.cpp:119: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:128: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result