Compilare: main.cpp: In function 'long long int make_tree(int)': main.cpp:125:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(edges.size() >= n) { ~~~~~~~~~~~~~^~~~ main.cpp: In function 'char nextch()': main.cpp:15:34: 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, MAXBUF, fi); ^