Compilare: main.cpp:41:25: warning: multi-character character constant [-Wmultichar] fout << v.size() << '/n'; ^~~~ main.cpp: In function 'int main()': main.cpp:37:26: warning: 'r' may be used uninitialized in this function [-Wmaybe-uninitialized] else prec[r] = v[r-1];