Compilare: user.cpp: In function ‘bool Euler(int)’: user.cpp:49: warning: comparison between signed and unsigned integer expressions user.cpp:57: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:86: warning: comparison between signed and unsigned integer expressions user.cpp:63: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:64: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:66: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result user.cpp:70: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result user.cpp:77: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result user.cpp: In function ‘bool Euler(int)’: user.cpp:29: warning: ‘firstt’ may be used uninitialized in this function /tmp/cczGaQpT.o: In function `main': user.cpp:(.text+0xae6): warning: the `gets' function is dangerous and should not be used.