Compilare: main.cpp: In function 'void find_next(int)': main.cpp:21:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (p1 < m[l].size() && p2 < m[l + 1].size()) { ~~~^~~~~~~~~~~~~ main.cpp:21:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (p1 < m[l].size() && p2 < m[l + 1].size()) { ~~~^~~~~~~~~~~~~~~~~