src.cpp:8:27: error: size of array 'a' is too large
int l,n,a[1000000][1000000],b[1000000];
^
src.cpp: In function 'void nhap()':
src.cpp:14:8: error: 'a' was not declared in this scope
fi>>a[i][j];
^
src.cpp: In function 'void xuli()':
src.cpp:21:11: error: 'a' was not declared in this scope
if (max<a[i][1]-a[i][0]) max=a[i][1]-a[i][0];
^
src.cpp:25:14: error: 'a' was not declared in this scope
for (int j=a[i-1][0];j<=a[i-1][1];j++){
^