Compilare: user.cpp: In function ‘int main()’: user.cpp:60:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < g[a].size(); i++) ^ user.cpp:40:12: warning: unused variable ‘j’ [-Wunused-variable] int i, j, a, b, c; ^ user.cpp:41:39: 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:42:41: 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: In function ‘void read(int&)’: user.cpp:9:35: 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);\ ^ user.cpp:30:66: note: in expansion of macro ‘nxt’ while((buf[pos] < '0' || buf[pos] > '9') && buf[pos] != '-') nxt(); ^ user.cpp:9:35: 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);\ ^ user.cpp:33:5: note: in expansion of macro ‘nxt’ nxt(); ^ user.cpp:9:35: 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);\ ^ user.cpp:34:82: note: in expansion of macro ‘nxt’ while(buf[pos] >= '0' && buf[pos] <= '9') { val = val * 10 + buf[pos] - '0'; nxt(); } ^