Compilare: user.cpp: In function ‘void flip(int, bool)’: user.cpp:11:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<M;i++) ^ user.cpp:14:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<N;i++) ^ user.cpp: In function ‘int main()’: user.cpp:20:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<N;i++) ^ user.cpp:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<M;j++) ^ user.cpp:23:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<N;i++) ^ user.cpp:26:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<M;j++) ^ user.cpp:31:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<N;i++) ^ user.cpp:34:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<M;j++) ^ user.cpp:39:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<N;i++) ^ user.cpp:40:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<M;j++) ^ user.cpp:42:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<N;i++) ^ user.cpp:45:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<M;j++) ^