Compilare: user.cpp: In function ‘void Down(int, int, int)’: user.cpp:16:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k == n) ^ user.cpp:21:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i <= nr; ++i) g << sol[i] << ' '; ^ user.cpp: In function ‘int main()’: user.cpp:49:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i <= n*(n+1)/2; ++i) f >> a[i]; ^ user.cpp:50:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = (n-1)*(n-1)/2 + 1; i <= n*(n+1)/2; ++i) b[i] = 1; ^