Compilare: user.cpp: In function ‘void check(int)’: user.cpp:45:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[ind].size(); ++i) ^ user.cpp:48:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < g[crt].size(); ++j) ^ user.cpp:60:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < v[i].size() && !ok && i != ind; ++j) ^ user.cpp: In function ‘int main()’: user.cpp:75:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("copii.in","r",stdin); ^ user.cpp:76:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("copii.out","w",stdout); ^ user.cpp:78:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &n); ^ user.cpp:81:30: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] for (gets(A+1), j = 1; j <= n; ++j) ^ /tmp/ccqD8UgK.o: In function `main': user.cpp:(.text.startup+0x80): warning: the `gets' function is dangerous and should not be used.