Compilare: main.cpp: In function 'void Back(int)': main.cpp:30:23: warning: suggest parentheses around comparison in operand of '&' [-Wparentheses] if (p >= a & si == sj) { ~~^~~~ main.cpp: In function 'int main()': main.cpp:58:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < sol.size(); i++) ~~^~~~~~~~~~~~