Compilare: user.cpp: In function ‘int main()’: user.cpp:50:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < v[0].v.size(); i++) ^ user.cpp:66:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j < v[a].v.size(); j++) ^ user.cpp:30:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dijkstra.in", "r", stdin); ^ user.cpp:31:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dijkstra.out", "w", stdout); ^ user.cpp:32:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:41:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &a, &b, &c); ^