Compilare: main.cpp: In function 'void ReadData()': main.cpp:39:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("dijkstra.in", "rt", stdin); ^ main.cpp:42:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] for(scanf("%d %d", &N, &M), i=1; i<=M; ++i) ^ main.cpp:44:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &a, &b, &c); ^ main.cpp: In function 'void WriteSolution()': main.cpp:131:42: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("dijkstra.out", "wt", stdout); ^