Compilare: main.cpp: In function 'int main()': main.cpp:12:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ccm.in", "r", stdin); ^ main.cpp:13:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ccm.out", "w", stdout); ^ main.cpp:15:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &n, &m, &e); ^ main.cpp:18:74: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] for(int i = 1; i <= e ; ++i) scanf("%d%d", &x, &y), v[x].push_back(y); ^