Compilare: user.cpp:9:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() { ^ user.cpp: In function ‘int main()’: user.cpp:25:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < t.size(); i++) { ^ user.cpp:30:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < t.size(); i++) { ^ user.cpp:32:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < t[i].size(); j++) { ^