Staff from Cognizant Technology Solutions helping visitors snap a wefie in front of the 105mm Japanese cannon at the Istana during its May Day open house yesterday. The IT services firm was raising funds for the President's Challenge by running a photo booth with various props. The Istana hosted over 11,400 guests who enjoyed musical and dance performances as well as tours of the Istana grounds and main building. President Tony Tan Keng Yam and his wife Mary joined in the activities as they greeted visitors and watched performances. Primary school teacher Benjamin Sim, 43, said: "It's my first time at the Istana... and it's a really nice day to come. It's grander than I thought it would be."