Compilare: user.cpp: In function ‘int main()’: user.cpp:13:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("abc2.in","r",stdin); ^ user.cpp:14:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("abc2.out","w",stdout); ^ user.cpp:16:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(sir); ^ user.cpp:15:12: warning: ‘l’ may be used uninitialized in this function [-Wmaybe-uninitialized] int l1,l,hash1=0,hash2=0,a1=1,a2=1,sol=0; ^ /tmp/ccv2SE5L.o: In function `main': user.cpp:(.text.startup+0x56): warning: the `gets' function is dangerous and should not be used.