/in/foo.cc: In function 'void add(int, int)':
/in/foo.cc:11:11: warning: unused variable 'j' [-Wunused-variable]
     int i,j;
           ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:41:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
     for(i=49;a[n][i]==0;--i);
     ^~~
/in/foo.cc:42:9: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
         for(j=i;j>=0;--j)
         ^~~