Compilare: user.cpp:10:9: warning: suggest parentheses around ‘+’ inside ‘<<’ [-Wparentheses] char a[1<<20+5]; ^ user.cpp: In function ‘void solve()’: user.cpp:40:9: warning: unused variable ‘i’ [-Wunused-variable] int i,j; ^ user.cpp:40:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j; ^ user.cpp: In function ‘int main()’: user.cpp:80:41: warning: too many arguments for format [-Wformat-extra-args] for (i=1;i<=n-1;i++) fprintf(g,"0",a); ^ user.cpp:51:22: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&n); ^ user.cpp:63:27: warning: array subscript is below array bounds [-Warray-bounds] for (i=0;i<cn;i++) a[i] = '0'; ^