Compilare: main.cpp: In function 'bool rec(int)': main.cpp:13:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<e[ind].size();i++){ ~^~~~~~~~~~~~~~ main.cpp:21:31: warning: suggest parentheses around assignment used as truth value [-Wparentheses] return vis[ind]=1; ~~~~~~~~^~ main.cpp:26:19: warning: suggest parentheses around assignment used as truth value [-Wparentheses] return vis[ind]=0; ~~~~~~~~^~ main.cpp: In function 'int main()': main.cpp:30:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("implicit.out","w",stdout); ^ main.cpp:31:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("messcore.in","r",stdin); ^