A basic barometer of economic activity in this tidy town south of Moscow is the pirozhok, a small pie filled with cabbage and meat that is a staple of the Russian diet. In good times they sell briskly, snapped up by hungry commuters at Arina’s Hangout, a tiny shop near the train station. But sales are down by almost half, a gloomy reflection of Russia’s economic slump. “There were just physically fewer people,” said Irina A. Safonova, the owner of the shop, which on a recent weekday was serving pies to a slow trickle of customers. “We used to have lines. Now look at it.” Russians are experiencing the first sustained decline in living standards in the 15 years since President Vladimir V. Putin came to power. The ruble has fallen by half against the dollar, driven by the plunging price of oil, the lifeblood of Russia’s economy. As a result, prices of imported goods have shot up, making tea, instant coffee, children’s clothes and back-to-school backpacks suddenly, jarringly expensive.