import std.stdio, std.conv, std.string, std.array, std.range, std.algorithm, std.container;
import std.math, std.random, std.bigint, std.datetime, std.format;
void main(string[] args){ if(args.length > 1) if(args[1] == "-debug") DEBUG = 1; solve(); } bool DEBUG = 0; 
void log(A ...)(lazy A a){ if(DEBUG) print(a); }
void print(){ writeln(""); } void print(T)(T t){ writeln(t); } void print(T, A ...)(T t, A a){ write(t, " "), print(a); }
string unsplit(T)(T xs){ return xs.array.to!(string[]).join(" "); }
string scan(){ static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res; }
T scan(T)(){ return scan.to!T; } T[] scan(T)(int n){ return n.iota.map!(i => scan!T()).array; }
T lowerTo(T)(ref T x, T y){ if(x > y) x = y; return x; } T raiseTo(T)(ref T x, T y){ if(x < y) x = y; return x; }

// ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- //

void solve(){
    int na = scan!int, nb = scan!int, m = scan!int;
    long[] as = scan!long(na);
    long[] bs = scan!long(nb);

    S[] ss;
    foreach(j; 0 .. m) ss ~= S(scan!int - 1, scan!int - 1, scan!long);

    long amin = as[0], bmin = bs[0];
    foreach(a; as) amin.lowerTo(a);
    foreach(b; bs) bmin.lowerTo(b);

    long ans = amin + bmin;
    foreach(s; ss){
        long tmp = as[s.x] + bs[s.y] - s.c;
        ans.lowerTo(tmp);
    }

    ans.writeln;
}

struct S{
    int x, y;
    long c;
}