Compilare: user.cpp: In function ‘void reverseGraph()’: user.cpp:27:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < edges.size(); i ++) { ^ user.cpp:31:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < edges.size(); i ++) { ^ user.cpp:32:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < edges[i].size(); j ++) { ^ user.cpp: In function ‘int main()’: user.cpp:94:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sol.size(); i ++) { ^ user.cpp:95:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < sol[i].size(); j ++) { ^ user.cpp:54:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in", "r", stdin); ^ user.cpp:55:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out", "w", stdout); ^ user.cpp:59:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:68:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^