Compilare: user.cpp: In function ‘void add_0_3()’: user.cpp:33:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(V[0][a]<s[1]&&a<V[0].size()) ^ user.cpp:43:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(V[3][b]<s[1]&&a<V[3].size()) ^ user.cpp:55:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(V[0][a]<s[i]&&a<V[0].size()) ^ user.cpp:63:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(V[3][b]<s[i]&&a<V[3].size()) ^ user.cpp:74:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(V[0][a]<s[i]&&a<V[0].size()) ^ user.cpp:82:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(V[3][b]<s[i]&&a<V[3].size()) ^ user.cpp:88:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(a!=V[0].size()) ^ user.cpp:96:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(a<V[0].size()) ^ user.cpp:107:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(b!=V[3].size()) ^ user.cpp:115:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(b<V[3].size()) ^ user.cpp: In function ‘int main()’: user.cpp:158:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=V[1].size();++i) ^ user.cpp:168:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=V[1].size();++i) ^ user.cpp:183:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=V[2].size();++i) ^ user.cpp:198:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=V[1].size();++i) ^