Compilare: main.cpp: In function 'void solve()': main.cpp:32:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < str.size(); i++){ ~~^~~~~~~~~~~~ main.cpp:42:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < str.size(); i++){ ~~^~~~~~~~~~~~ main.cpp: In function 'int gauss(int)': main.cpp:25:1: warning: control reaches end of non-void function [-Wreturn-type] } ^