Compilare: main.cpp: In function 'int main()': main.cpp:50:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ind[b[i] - '0'] < p[b[i] - '0'].size()) { ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~ main.cpp:56:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ind[j] < p[j].size() && p[j][ind[j]] < mn) ~~~~~~~^~~~~~~~~~~~~ main.cpp:60:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ind[j] < p[j].size() && p[j][ind[j]] == mn) ~~~~~~~^~~~~~~~~~~~~