Compilare: user.cpp: In function ‘int main()’: user.cpp:7:28: warning: unused variable ‘r’ [-Wunused-variable] int N,M,i,j,sp,sm,s,s2,r,a[100][100];s=0; ^ user.cpp:34:5: warning: assuming signed overflow does not occur when assuming that (X + c) < X is always false [-Wstrict-overflow] for(i=1;i<=N;i++) ^