Vlookup ? Comparison of 2 worksheets data then value is entered into 2nd worksheet

Please can someone help....


My first worksheet has


a1 0.5 b2
d2 0.6 c3
e4 1.3 f4
h6 0.5 s6



My second worksheet would be automatically populated

a1 no. from above b2
d5 "Not Found" c3
e4 "Not Found" g4
h6 no. from above s6


I want a syntax or similar that will automatically populate the second worksheet, only when the corresponding values are the same i.e. a1 b2
and if not ie d5 c3 and e4 f4, it states "Not Found"