Compilare: main.cpp: In function 'int main()': main.cpp:126:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k = 0; k < alph.size(); ++k) { ~~^~~~~~~~~~~~~ main.cpp: At global scope: main.cpp:67:13: warning: 'void enforced(int)' defined but not used [-Wunused-function] static void enforced(int ch) { ^~~~~~~~