import os

input = open(os.path.dirname(__file__) +
             "/input.txt", "r").read()

index = 0
index2 = 0
buf = []
for x in input:
    index += 1
    index2 += 1
    buf.append(x)
    if len(buf) == 4:
        if len(set(buf)) == 4:
            break
        else:
            buf.pop(0)

print(index)