Compilare: main.cpp: In function 'int main()': main.cpp:24:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(!stiva.empty() && l - i + 2 > m - stiva.size() && stiva.top() < s[i] - '0') ~~~~~~~~~~^~~~~~~~~~~~~~~~~~ main.cpp:28:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(l - i + 2 == m - stiva.size()) ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~