foo.c: In function 'main':
foo.c:18:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
     for (i = 0; l[i] != 0; i++)
     ^~~
foo.c:24:9: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
         int k=1;
         ^~~
foo.c:7:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s%s", a, b);
     ^~~~~~~~~~~~~~~~~~~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。