NEW DELHI (AP) — The United Nations is celebrating the sanitation gains made in India since Prime Minister Narendra Modi came to power in 2014 at a summit this week in New Delhi, but in Tamu Nagar, a slum just outside one of the city's poshest neighborhoods, hundreds of people rely on a single public toilet.

The numbers in the government's ambitious Swachh Bharat, or Clean India, program are staggering. India's population of 1.3 billion constituted 60 percent of the world's open defecation in 2014, when Modi was elected, but only 20 percent by 2018.

The $20 billion program concludes in 2019.

But the summit — with a keynote address by U.N. Secretary General Antonio Guterres on Tuesday — overshadows the struggles with open defecation that remain in the heart of India's capital.