for i in range(int(input())):
x=input()
x=int(x)
s=str(input())
u=str(input())
k=int(0)
j=int(0)
while j<(x-1):
if(s[j]==u[j]):
k=k+1
j=j+1
if(u[j]=='N'):
j=j+1
if((u[j]!=s[j])and(u[j]!='N')):
j=j+2
if(s[len(s)-1]==u[len(s)-1]):
k=k+1
print(int(k))