i want to dynamically SUM cells till a certain condition is reached.

Cell A1 has a value y

Cell B1 has value x1, B2 has value x2, B3 has value x3, B4 has value x4 and so on

I want to write a formula in cell C1 which will keep on summing x1, x2, x3 etc till the sum value is just greater than or equal to y

eg A1 = 100, B1 = 50, B2 = 49, B3 = 5, B4 = 10, B5 = 41 ...

so Cell C1 should give me the sum as (50+49+5) = 104 (ie keep on summing until the sum just becomes greater than or equal to 100)