Compilare: user.cpp: In function ‘int main()’: user.cpp:37:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=n;i++) ^ user.cpp:43:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=n-2;i++) ^ user.cpp:45:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=i+1;j<=n-1;j++) ^ user.cpp: In function ‘int exista(int, int, int, int)’: user.cpp:29:1: warning: control reaches end of non-void function [-Wreturn-type] } ^