Compilare: main.cpp: In function 'int main()': main.cpp:30:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.length();i++) ~^~~~~~~~~~~ main.cpp:34:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=i+1;j<s.length();j++) ~^~~~~~~~~~~ main.cpp:35:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=j+1;k<s.length();k++) ~^~~~~~~~~~~