Compilare: main.cpp: In function 'int main()': main.cpp:20:9: warning: unused variable 'a' [-Wunused-variable] int a = s[i][0] - 'a', b = s[i][s[i].size() - 1] - 'a'; ^ main.cpp:20:28: warning: unused variable 'b' [-Wunused-variable] int a = s[i][0] - 'a', b = s[i][s[i].size() - 1] - 'a'; ^