Compilare: user.cpp: In function ‘char nextch()’: user.cpp:19:34: 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); ^ user.cpp: In function ‘int main()’: user.cpp:137:20: warning: ‘first’ may be used uninitialized in this function [-Wmaybe-uninitialized] addEdge(i, first + n, 1); ~~~~~~~^~~~~~~~~~~~~~~~~