Compilare: user.cpp: In function ‘void tarjan(int)’: user.cpp:18:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<g[u].size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:64:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<sg[sv[i]].size();++j) ^ user.cpp:67:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0;k<g[u].size();++k) ^ user.cpp:82:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<sg[sv[i]].size();++j) c[sg[sv[i]][j]]=1; ^ user.cpp:85:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<sg[sv[i]].size();++j) ^ user.cpp:88:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0;k<g[u].size();++k) ^ user.cpp:44:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("drumuri5.in","r",stdin); ^ user.cpp:45:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("drumuri5.out","w",stdout); ^ user.cpp:47:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&N,&m); ^ user.cpp:51:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&u,&v); ^