Compilare: main.cpp: In function 'int main()': main.cpp:25:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(a=0;nr<k&&a<prime.size();a++) if(x%prime[a]==0) { nr++; if(nr==k) val=prime[a];} ~^~~~~~~~~~~~~ main.cpp:34:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(a=0;nr<k&&a<prime.size();a++) if(x%prime[a]==0) { nr++; if(nr==k) val=prime[a];} ~^~~~~~~~~~~~~ main.cpp:26:15: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized] g<<val; ^