Compilare: main.cpp: In function 'void dfs(int, int)': main.cpp:84:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < l1[el].size(); ++i) ~~^~~~~~~~~~~~~~~ main.cpp: In function 'void union_find()': main.cpp:91:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < x1.size(); ++i) { ~~^~~~~~~~~~~ main.cpp:104:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < x2.size(); ++i) { ~~^~~~~~~~~~~