/in/foo.cc: In function 'void floyd()':
/in/foo.cc:108:9: warning: iteration 2 invokes undefined behavior [-Waggressive-loop-optimizations]
 mp[i][j]=min(mp[i][j],mp[i][k]+mp[k][j]);
 ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc:107:14: note: within this loop
 for(int j=1;j<=3;j++)
             ~^~~
/in/foo.cc:104:19: warning: array subscript is above array bounds [-Warray-bounds]
 mp[1][2]=a;mp[2][3]=b;
            ~~~~~~~^
/in/foo.cc:109:15: warning: array subscript is above array bounds [-Warray-bounds]
 ans[3]=mp[1][3];
        ~~~~~~~^