Compilare: main.cpp: In function 'int main()': main.cpp:46:13: warning: unused variable 'val' [-Wunused-variable] int val = it.first, i = it.second.first, j = it.second.second; ^~~ main.cpp:66:13: warning: 'y' may be used uninitialized in this function [-Wmaybe-uninitialized] rec(x,y); ^ main.cpp:66:13: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]