Compilare: user.cpp: In function ‘void afis(std::vector<std::vector<bool> >)’: user.cpp:30:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<s.size(); ++i) { ^ user.cpp:31:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<s[i].size(); ++j) cout<<s[i][j]; ^ user.cpp: In function ‘void cnt(std::vector<std::vector<bool> >)’: user.cpp:39:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,j=0,k;i<s.size() && j<s[0].size();) { ^ user.cpp:39:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,j=0,k;i<s.size() && j<s[0].size();) { ^ user.cpp:40:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k=i; k<s.size() && !s[k][j]; ++k); ^ user.cpp:41:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k==s.size()) { ^ user.cpp:46:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k=i+1; k<s.size(); ++k) if(s[k][j]) for(int l=j; l<=m*n;++l) s[k][l]=s[k][l]^s[i][l]; ^ user.cpp:50:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,j; i<s.size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:67:11: warning: unused variable ‘nv’ [-Wunused-variable] int nv=0; ^