Compilare: user.cpp: In function ‘bool bfs()’: user.cpp:30:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < m[x].size(); ++i) { ^ user.cpp: In function ‘void update_flow()’: user.cpp:43:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<m[D].size();++i) { ^ user.cpp: In function ‘int main()’: user.cpp:117:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<m[i].size();++j) { ^ user.cpp:130:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<m[D].size();++i) { ^ user.cpp:76:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("smart.in","r",stdin); ^ user.cpp:77:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("smart.out","w",stdout); ^ user.cpp:79:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&s); ^ user.cpp:81:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c",&c); ^ user.cpp:83:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c",&a[i][j]); ^