Compilare: main.cpp: In function 'int main()': main.cpp:9:9: warning: unused variable 'a' [-Wunused-variable] int a,b,i,j,l,C,N,M,x1,x2,y1,y2; ^ main.cpp:9:11: warning: unused variable 'b' [-Wunused-variable] int a,b,i,j,l,C,N,M,x1,x2,y1,y2; ^ main.cpp:9:17: warning: unused variable 'l' [-Wunused-variable] int a,b,i,j,l,C,N,M,x1,x2,y1,y2; ^