Compilare: main.cpp: In function 'int main()': main.cpp:203:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < G[node].size(); i++) ~~^~~~~~~~~~~~~~~~ main.cpp: In function 'char nextch()': main.cpp:27:36: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buf, BUF_SIZE, 1, fi); ^