Compilare: user.cpp: In function ‘void eraseEdge(int, int)’: user.cpp:26:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < vec[a].size(); ++ i) ^ user.cpp:33:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < vec[b].size(); ++ i) ^ user.cpp: In function ‘int findCommon(std::vector<int>, std::vector<int>)’: user.cpp:44:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v1.size(); ++ i) ^ user.cpp:45:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < v2.size(); ++ j) ^ user.cpp: In function ‘int main()’: user.cpp:53:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("puzzle2.in", "r", stdin); ^ user.cpp:54:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("puzzle2.out", "w", stdout); ^ user.cpp:56:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i %i", &n, &m); ^ user.cpp:59:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i %i", &a, &b); ^ user.cpp:141:9: warning: ‘c’ may be used uninitialized in this function [-Wmaybe-uninitialized] for (int j = 1; j <= c; ++ j) ^ user.cpp:105:22: warning: ‘r’ may be used uninitialized in this function [-Wmaybe-uninitialized] sol = new int*[r + 5]; ^