import sys
a = int(sys.stdin.readline())
b = int(sys.stdin.readline())
d = 0
for i in range(a):
while (b != 0):
c = b % 10
d += int(c)
round(b, 0)
b /= 10
print(d)
aW1wb3J0IHN5cwphID0gaW50KHN5cy5zdGRpbi5yZWFkbGluZSgpKQpiID0gaW50KHN5cy5zdGRpbi5yZWFkbGluZSgpKQpkID0gMApmb3IgaSBpbiByYW5nZShhKToKICAgIHdoaWxlIChiICE9IDApOgogICAgICAgIGMgPSBiICUgMTAKICAgICAgICBkICs9IGludChjKQogICAgICAgIHJvdW5kKGIsIDApCiAgICAgICAgYiAvPSAxMApwcmludChkKQ==