Compilare: user.cpp: In function ‘bool ver(int, int)’: user.cpp:30:67: warning: array subscript has type ‘char’ [-Wchar-subscripts] int pa=((s[i1].first[0]==s[i2].first[0])?0:nxt[0][s[i1].first[0]]); ^ user.cpp:33:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i==s[i1].first.size()-1)break; ~^~~~~~~~~~~~~~~~~~~~~~ user.cpp:34:32: warning: array subscript has type ‘char’ [-Wchar-subscripts] pa=nxt[pa][s[i1].first[i+1]]; ^ user.cpp: In function ‘int main()’: user.cpp:52:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<s[i].first.size();j++) ~^~~~~~~~~~~~~~~~~~ user.cpp:57:33: warning: array subscript has type ‘char’ [-Wchar-subscripts] nxt[k][s[i].first[j]]=j; ^