Compilare: main.cpp: In function 'int main()': main.cpp:11:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<a.size();++i) ~^~~~~~~~~ main.cpp:15:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<b.size();++i) ~^~~~~~~~~ main.cpp:21:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<a.size();++i) ~^~~~~~~~~ main.cpp:30:1: warning: this 'for' clause does not guard... [-Wmisleading-indentation] for (i=1;i<=st[0];++i) ^~~ main.cpp:32:5: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for' return 0; ^~~~~~