Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:20:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( xx <= 0 || xx >= mst1.size() ) continue; ^ user.cpp:21:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( yy <= 0 || yy >= mst2.size() ) continue; ^ user.cpp: In function ‘int main()’: user.cpp:55:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1; i <= mst1.size(); i ++ ) ^ user.cpp:56:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 1; j <= mst2.size(); j ++ ) ^ user.cpp:60:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1; i < mst1.size(); i ++ ) { ^ user.cpp:61:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 1; j < mst2.size(); j ++ ) { ^