/in/foo.c: In function 'main':
/in/foo.c:17:5: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
   if(b1==b2)//列相同 
     ^
/in/foo.c:25:6: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
    if(a1==a2)//行相同
      ^
/in/foo.c:75:3: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   for(i=2;i<=l;i++)
   ^~~
/in/foo.c:77:4: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
    printf("\n");
    ^~~~~~