Compilare: user.cpp: In function ‘int main()’: user.cpp:31:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (mn=1; mn<=n&&dif.size()<l; ++mn) ^ user.cpp:38:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (last=mn; last<=n&&dif.size()<u; ++last) ^ user.cpp:38:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (last=mn; last<=n&&dif.size()<u; ++last) ^ user.cpp:47:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (dif.size()<l) ^ user.cpp:65:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (last=last+1; last<=n; ++last) ^ user.cpp:76:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (dif.size()>=l) ^