Compilare: main.cpp: In function 'void read()': main.cpp:18:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=a; j<=N; j++) ~^~~ main.cpp:20:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=1;j<=b;j++) ~^~~ main.cpp:24:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=a; j<=b; j++) ~^~~ main.cpp: In function 'int main()': main.cpp:38:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=P;j<=N;j++) ~^~~ main.cpp:41:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=1;j<=Q;j++) ~^~~ main.cpp:45:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=P;j<=N;j++) ~^~~ main.cpp:48:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=1;j<=Q;j++) ~^~~ main.cpp:53:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=P;i<=Q&&ok==1;i++) ~^~~