Compilare: user.cpp: In function ‘bool solve(int, int)’: user.cpp:4:7: warning: unused variable ‘i’ [-Wunused-variable] int i, dc; ^ user.cpp: In function ‘int main()’: user.cpp:27:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("invers.in", "r", stdin); ^ user.cpp:28:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("invers.out", "w", stdout); ^ user.cpp:30:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &t); ^ user.cpp:33:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/ccL4aIZj.o: In function `main': user.cpp:(.text.startup+0x94): warning: the `gets' function is dangerous and should not be used.