Which measure is play before measure 5 the second time?

Measure is a segment of time within a piece of music defined by a given number of beats. Each measure is separated by a bar. Within each measure, beats are represented by a particular note value and the boundaries of the bar are indicated by vertical bar lines. Dividing music into bars provides regular reference points to pinpoint locations within a piece of music. It also makes written music easier to follow, since each bar of staff symbols can be read and played as a batch.