Compilare: main.cpp: In function 'int main()': main.cpp:43:42: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bellmanford.in", "r", stdin); ^ main.cpp:44:44: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bellmanford.out", "w", stdout); ^ main.cpp: In function 'void read(int&)': main.cpp:7:35: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buf, 1, bufs, stdin);\ ^ main.cpp:21:66: note: in expansion of macro 'nxt' while((buf[pos] < '0' || buf[pos] > '9') && buf[pos] != '-') nxt(); ^~~ main.cpp:7:35: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buf, 1, bufs, stdin);\ ^ main.cpp:24:5: note: in expansion of macro 'nxt' nxt(); ^~~ main.cpp:7:35: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buf, 1, bufs, stdin);\ ^ main.cpp:25:82: note: in expansion of macro 'nxt' while(buf[pos] >= '0' && buf[pos] <= '9') { val = val * 10 + buf[pos] - '0'; nxt(); } ^~~