Compilare: main.cpp: In function 'int main()': main.cpp:17:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<s.size()) ~^~~~~~~~~ main.cpp:25:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<s.size() and s[i]>='a' and s[i]<='z') ~^~~~~~~~~ main.cpp:27:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<s.size() and s[i]>='0' and s[i]<='9') ~^~~~~~~~~ main.cpp:34:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<s.size() and s[i]>='0' and s[i]<='9') ~^~~~~~~~~ main.cpp:43:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<sol.size();++i) ~^~~~~~~~~~~