Compilare: user.cpp: In function ‘bool solve(int, int, int)’: user.cpp:10:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(j==s.size()) ^ user.cpp:16:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i==S.size()) ^ user.cpp: In function ‘int main()’: user.cpp:34:11: warning: unused variable ‘i’ [-Wunused-variable] int n,i,j; ^ user.cpp:34:13: warning: unused variable ‘j’ [-Wunused-variable] int n,i,j; ^