Compilare: user.cpp: In function ‘int main()’: user.cpp:22:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s1.size(); i++) { ^ user.cpp:26:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s2.size(); i++) { ^ user.cpp:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 2; i < a.size(); i++) { ^ user.cpp:46:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < b.size(); i++) { ^ user.cpp:55:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k == a.size() - 1) { ^ user.cpp:66:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sol.size(); i++) { ^