Compilare: main.cpp: In function 'int main()': main.cpp:69:33: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d%d%d ",&n,&m,&q); ^ main.cpp:73:21: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(c+1,N,fin); ^ main.cpp:151:43: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d%d%d%d",&x1,&y1,&x2,&y2); ^ main.cpp: In function 'void dfs(int)': main.cpp:17:9: warning: '#'target_mem_ref' not supported by dump_expr#<expression error>' may be used uninitialized in this function [-Wmaybe-uninitialized] int ok[100]; ^~ main.cpp:23:19: warning: '#'target_mem_ref' not supported by dump_expr#<expression error>' may be used uninitialized in this function [-Wmaybe-uninitialized] if(ok[i]==ok[j]) ~~~~^ In file included from /usr/include/stdio.h:936:0, from /usr/include/c++/6/cstdio:42, from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:46, from main.cpp:1: In function 'char* fgets(char*, int, FILE*)', inlined from 'int main()' at main.cpp:73:21: /usr/include/x86_64-linux-gnu/bits/stdio2.h:261:58: warning: call to '__fgets_chk_warn' declared with attribute warning: fgets called with bigger size than length of destination buffer return __fgets_chk_warn (__s, __bos (__s), __n, __stream); ^