Compilare: user.cpp: In function ‘int main(int, const char**)’: user.cpp:34:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < a.size(); ++i) ^ user.cpp:48:33: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 2 has type ‘std::vector<int>::size_type {aka unsigned int}’ [-Wformat=] printf("%lu\n", b.size() - 1); ^ user.cpp:52:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(front <= b.size()) ^ user.cpp:54:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(front == b.size() - 1) ^ user.cpp:20:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("politic.in", "r", stdin); ^ user.cpp:21:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("politic.out", "w", stdout); ^ user.cpp:23:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:26:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^