Compilare: main.cpp: In function 'int main()': main.cpp:22:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++){ ~~^~~~~~~~~~ main.cpp:30:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++){ ~~^~~~~~~~~~ main.cpp:41:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(fr[j - 'a'] == minim && i + 1 < s.size() && s[i + 1] != j) ~~~~~~^~~~~~~~~~ main.cpp:48:19: warning: 'mn' may be used uninitialized in this function [-Wmaybe-uninitialized] fr[mn - 'a']++; ~~~^~~~~