Compilare: main.cpp: In function 'void add(nod*, int)': main.cpp:22:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(pos==word.size()) ~~~^~~~~~~~~~~~~ main.cpp: In function 'bool pop(nod*, int)': main.cpp:36:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(pos==word.size()) ~~~^~~~~~~~~~~~~ main.cpp: In function 'int count_words(nod*, int)': main.cpp:53:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(pos==word.size()) ~~~^~~~~~~~~~~~~ main.cpp: In function 'int common_prefix(nod*, int)': main.cpp:61:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(pos==word.size()) ~~~^~~~~~~~~~~~~