import std.stdio, std.string, std.conv, std.algorithm;
import std.range, std.array, std.math, std.typecons;

int n;
string s, t;

void main() {
    scan(n);
    scan(s);
    scan(t);

    iota(n).map!(i => s[i] != t[i]).sum.writeln;
}


void scan(T...)(ref T args) {
    auto line = readln.split;
    foreach (ref arg ; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}